[LinuxBIOS] [PATCH] Geode LX CAS setting fix

[Marc Jones]

See attached patch.
Thanks!
Marc

-- 
Marc Jones
Senior Software Engineer
[phone] Office
mailto:[e-mail]
http://www.amd.com/embeddedprocessors

This patch fixes the CAS map for -.5 and -1 CAS settings. The -.5 setting should only shift the mask one bit, not two.

Signed-off-by: Marc Jones <[e-mail]>


Index: LinuxBIOSv2/src/northbridge/amd/lx/raminit.c
===================================================================
--- LinuxBIOSv2.orig/src/northbridge/amd/lx/raminit.c	2007-06-13 17:01:03.000000000 -0600
+++ LinuxBIOSv2/src/northbridge/amd/lx/raminit.c	2007-06-13 17:01:03.000000000 -0600
@@ -151,7 +151,7 @@
 	}
 
 	/* I don't think you need this check.
-	   if (spd_byte0 < 0xA0 || spd_byte0 < 0xA0){
+	   if (spd_byte0 >= 0xA0 || spd_byte1 >= 0xA0){
 	   print_debug("DIMM overclocked. Check GeodeLink Speed\n");
 	   POST_CODE(POST_PLL_MEM_FAIL);
 	   __asm__       __volatile__("hlt\n");
@@ -231,7 +231,7 @@
 ;*	Destroys: We really use everything !
 ;*****************************************************************************/
 	uint16_t glspeed, dimm_speed;
-	uint8_t spd_byte, casmap0, casmap1;
+	uint8_t spd_byte, casmap0, casmap1, casmap_shift;
 	msr_t msr;
 
 	glspeed = GeodeLinkSpeed();
@@ -246,25 +246,24 @@
 			dimm_speed = 2 * (10000 / (((spd_byte >> 4) * 10) +
 						(spd_byte & 0x0F)));
 			if (dimm_speed >= glspeed) {
+				casmap_shift = 1; /* -.5 is a shift of 1 */
 				/* IF -1 timing is supported, check -1 timing > GeodeLink */
 				spd_byte = spd_read_byte(DIMM0, SPD_SDRAM_CYCLE_TIME_3RD);
 				if (spd_byte != 0) {
 					/* Turn SPD ns time into MHZ. Check what the asm does to this math. */
 					dimm_speed = 2 * (10000 / (((spd_byte >> 4) * 10) + (spd_byte & 0x0F)));
-					if (dimm_speed <= glspeed) {
-						/* set we can use -.5 timing but not -1 */
-						spd_byte = 31 - __builtin_clz((uint32_t) casmap0);
-						/* just want bits in the lower byte since we have to cast to a 32 */
-						casmap0 &= 0xFF << (--spd_byte);
+					if (dimm_speed >= glspeed) {
+						casmap_shift = 2; /* -1 is a shift of 2 */
 					}
-				}	/*MIN_CYCLE_10 !=0 */
+				}	/* SPD_SDRAM_CYCLE_TIME_3RD (-1) !=0 */
 			} else {
-				/* Timing_05 < GLspeed, can't use -.5 or -1 timing */
-				spd_byte = 31 - __builtin_clz((uint32_t) casmap0);
-				/* just want bits in the lower byte since we have to cast to a 32 */
-				casmap0 &= 0xFF << (spd_byte);
+				casmap_shift = 0;
 			}
-		}		/*MIN_CYCLE_05 !=0 */
+		}	/* SPD_SDRAM_CYCLE_TIME_2ND (-.5) !=0 */
+		/* set the casmap based on the shift to limit possible CAS settings */
+		spd_byte = 31 - __builtin_clz((uint32_t) casmap0);
+		/* just want bits in the lower byte since we have to cast to a 32 */
+		casmap0 &= 0xFF << (spd_byte - casmap_shift);
 	} else {		/* No DIMM */
 		casmap0 = 0;
 	}
@@ -278,25 +277,25 @@
 			/* Turn SPD ns time into MHZ. Check what the asm does to this math. */
 			dimm_speed = 2 * (10000 / (((spd_byte >> 4) * 10) + (spd_byte & 0x0F)));
 			if (dimm_speed >= glspeed) {
+				casmap_shift = 1; /* -.5 is a shift of 1 */
 				/* IF -1 timing is supported, check -1 timing > GeodeLink */
 				spd_byte = spd_read_byte(DIMM1, SPD_SDRAM_CYCLE_TIME_3RD);
 				if (spd_byte != 0) {
 					/* Turn SPD ns time into MHZ. Check what the asm does to this math. */
 					dimm_speed = 2 * (10000 / (((spd_byte >> 4) * 10) + (spd_byte & 0x0F)));
-					if (dimm_speed <= glspeed) {
-						/* set we can use -.5 timing but not -1 */
-						spd_byte = 31 - __builtin_clz((uint32_t) casmap1);
-						/* just want bits in the lower byte since we have to cast to a 32 */
-						casmap1 &= 0xFF << (--spd_byte);
+					if (dimm_speed >= glspeed) {
+						casmap_shift = 2; /* -1 is a shift of 2 */
 					}
-				}	/*MIN_CYCLE_10 !=0 */
+					/* note that the -1 result doesn't need to change the available CAS map */
+				}	/* SPD_SDRAM_CYCLE_TIME_3RD (-1) !=0 */
 			} else {
-				/* Timing_05 < GLspeed, can't use -.5 or -1 timing */
-				spd_byte = 31 - __builtin_clz((uint32_t) casmap1);
-				/* just want bits in the lower byte since we have to cast to a 32 */
-				casmap1 &= 0xFF << (spd_byte);
+				casmap_shift = 0;
 			}
-		}		/*MIN_CYCLE_05 !=0 */
+		}	/* SPD_SDRAM_CYCLE_TIME_2ND (-.5) !=0 */
+		/* set the casmap based on the shift to limit possible CAS settings */
+		spd_byte = 31 - __builtin_clz((uint32_t) casmap1);
+		/* just want bits in the lower byte since we have to cast to a 32 */
+		casmap1 &= 0xFF << (spd_byte - casmap_shift);
 	} else {		/* No DIMM */
 		casmap1 = 0;
 	}

[ron minnich]

Acked-by: Ronald G. Minnich <[e-mail]>

Note: I have not tested this on hardware. But I can bet Marc has :-)
This just convinces me that DRAM really is black magic :-)

On 6/13/07, Marc Jones <[e-mail]> wrote:
> See attached patch.
> Thanks!
> Marc
>
> This patch fixes the CAS map for -.5 and -1 CAS settings. The -.5 setting should only shift the mask one bit, not two.
>
> Signed-off-by: Marc Jones <[e-mail]>
>
> Index: LinuxBIOSv2/src/northbridge/amd/lx/raminit.c
> ===================================================================
> --- LinuxBIOSv2.orig/src/northbridge/amd/lx/raminit.c   2007-06-13 17:01:03.000000000 -0600
> +++ LinuxBIOSv2/src/northbridge/amd/lx/raminit.c        2007-06-13 17:01:03.000000000 -0600
> @@ -151,7 +151,7 @@
>         }
>
> /* I don't think you need this check.
> -          if (spd_byte0 < 0xA0 || spd_byte0 < 0xA0){
> +          if (spd_byte0 >= 0xA0 || spd_byte1 >= 0xA0){
>            print_debug("DIMM overclocked. Check GeodeLink Speed\n");
>            POST_CODE(POST_PLL_MEM_FAIL);
>            __asm__       __volatile__("hlt\n");
> @@ -231,7 +231,7 @@
>  ;*     Destroys: We really use everything !
>  ;*****************************************************************************/
>         uint16_t glspeed, dimm_speed;
> -       uint8_t spd_byte, casmap0, casmap1;
> +       uint8_t spd_byte, casmap0, casmap1, casmap_shift;
>         msr_t msr;
>
> glspeed = GeodeLinkSpeed();
> @@ -246,25 +246,24 @@
>                         dimm_speed = 2 * (10000 / (((spd_byte >> 4) * 10) +
>                                                 (spd_byte & 0x0F)));
>                         if (dimm_speed >= glspeed) {
> +                               casmap_shift = 1; /* -.5 is a shift of 1 */
>                                 /* IF -1 timing is supported, check -1 timing > GeodeLink */
>                                 spd_byte = spd_read_byte(DIMM0, SPD_SDRAM_CYCLE_TIME_3RD);
>                                 if (spd_byte != 0) {
>                                         /* Turn SPD ns time into MHZ. Check what the asm does to this math. */
>                                         dimm_speed = 2 * (10000 / (((spd_byte >> 4) * 10) + (spd_byte & 0x0F)));
> -                                       if (dimm_speed <= glspeed) {
> -                                               /* set we can use -.5 timing but not -1 */
> -                                               spd_byte = 31 - __builtin_clz((uint32_t) casmap0);
> -                                               /* just want bits in the lower byte since we have to cast to a 32 */
> -                                               casmap0 &= 0xFF << (--spd_byte);
> +                                       if (dimm_speed >= glspeed) {
> +                                               casmap_shift = 2; /* -1 is a shift of 2 */
>                                         }
> -                               }       /*MIN_CYCLE_10 !=0 */
> +                               }       /* SPD_SDRAM_CYCLE_TIME_3RD (-1) !=0 */
>                         } else {
> -                               /* Timing_05 < GLspeed, can't use -.5 or -1 timing */
> -                               spd_byte = 31 - __builtin_clz((uint32_t) casmap0);
> -                               /* just want bits in the lower byte since we have to cast to a 32 */
> -                               casmap0 &= 0xFF << (spd_byte);
> +                               casmap_shift = 0;
>                         }
> -               }               /*MIN_CYCLE_05 !=0 */
> +               }       /* SPD_SDRAM_CYCLE_TIME_2ND (-.5) !=0 */
> +               /* set the casmap based on the shift to limit possible CAS settings */
> +               spd_byte = 31 - __builtin_clz((uint32_t) casmap0);
> +               /* just want bits in the lower byte since we have to cast to a 32 */
> +               casmap0 &= 0xFF << (spd_byte - casmap_shift);
>         } else {                /* No DIMM */
>                 casmap0 = 0;
>         }
> @@ -278,25 +277,25 @@
>                         /* Turn SPD ns time into MHZ. Check what the asm does to this math. */
>                         dimm_speed = 2 * (10000 / (((spd_byte >> 4) * 10) + (spd_byte & 0x0F)));
>                         if (dimm_speed >= glspeed) {
> +                               casmap_shift = 1; /* -.5 is a shift of 1 */
>                                 /* IF -1 timing is supported, check -1 timing > GeodeLink */
>                                 spd_byte = spd_read_byte(DIMM1, SPD_SDRAM_CYCLE_TIME_3RD);
>                                 if (spd_byte != 0) {
>                                         /* Turn SPD ns time into MHZ. Check what the asm does to this math. */
>                                         dimm_speed = 2 * (10000 / (((spd_byte >> 4) * 10) + (spd_byte & 0x0F)));
> -                                       if (dimm_speed <= glspeed) {
> -                                               /* set we can use -.5 timing but not -1 */
> -                                               spd_byte = 31 - __builtin_clz((uint32_t) casmap1);
> -                                               /* just want bits in the lower byte since we have to cast to a 32 */
> -                                               casmap1 &= 0xFF << (--spd_byte);
> +                                       if (dimm_speed >= glspeed) {
> +                                               casmap_shift = 2; /* -1 is a shift of 2 */
>                                         }
> -                               }       /*MIN_CYCLE_10 !=0 */
> +                                       /* note that the -1 result doesn't need to change the available CAS map */
> +                               }       /* SPD_SDRAM_CYCLE_TIME_3RD (-1) !=0 */
>                         } else {
> -                               /* Timing_05 < GLspeed, can't use -.5 or -1 timing */
> -                               spd_byte = 31 - __builtin_clz((uint32_t) casmap1);
> -                               /* just want bits in the lower byte since we have to cast to a 32 */
> -                               casmap1 &= 0xFF << (spd_byte);
> +                               casmap_shift = 0;
>                         }
> -               }               /*MIN_CYCLE_05 !=0 */
> +               }       /* SPD_SDRAM_CYCLE_TIME_2ND (-.5) !=0 */
> +               /* set the casmap based on the shift to limit possible CAS settings */
> +               spd_byte = 31 - __builtin_clz((uint32_t) casmap1);
> +               /* just want bits in the lower byte since we have to cast to a 32 */
> +               casmap1 &= 0xFF << (spd_byte - casmap_shift);
>         } else {                /* No DIMM */
>                 casmap1 = 0;
>         }

[LinuxBIOS] Geode LX CAS setting fix

[Jordan Crouse]

On 13/06/07 17:51 -0700, ron minnich wrote:
> Acked-by: Ronald G. Minnich <[e-mail]>
>
> Note: I have not tested this on hardware. But I can bet Marc has :-)
> This just convinces me that DRAM really is black magic :-)

r2722.  And yes - it is all black magic, which is why Marc wears a 
black hat and is followed by a low fog as he walks the halls.

Jordan
> On 6/13/07, Marc Jones <[e-mail]> wrote:
> > See attached patch.
> > Thanks!
> > Marc
> >
> > This patch fixes the CAS map for -.5 and -1 CAS settings. The -.5 setting should only shift the mask one bit, not two.
> >
> > Signed-off-by: Marc Jones <[e-mail]>
> >
> > Index: LinuxBIOSv2/src/northbridge/amd/lx/raminit.c
> > ===================================================================
> > --- LinuxBIOSv2.orig/src/northbridge/amd/lx/raminit.c   2007-06-13 17:01:03.000000000 -0600
> > +++ LinuxBIOSv2/src/northbridge/amd/lx/raminit.c        2007-06-13 17:01:03.000000000 -0600
> > @@ -151,7 +151,7 @@
> >         }
> >
> > /* I don't think you need this check.
> > -          if (spd_byte0 < 0xA0 || spd_byte0 < 0xA0){
> > +          if (spd_byte0 >= 0xA0 || spd_byte1 >= 0xA0){
> >            print_debug("DIMM overclocked. Check GeodeLink Speed\n");
> >            POST_CODE(POST_PLL_MEM_FAIL);
> >            __asm__       __volatile__("hlt\n");
> > @@ -231,7 +231,7 @@
> >  ;*     Destroys: We really use everything !
> >  ;*****************************************************************************/
> >         uint16_t glspeed, dimm_speed;
> > -       uint8_t spd_byte, casmap0, casmap1;
> > +       uint8_t spd_byte, casmap0, casmap1, casmap_shift;
> >         msr_t msr;
> >
> > glspeed = GeodeLinkSpeed();
> > @@ -246,25 +246,24 @@
> >                         dimm_speed = 2 * (10000 / (((spd_byte >> 4) * 10) +
> >                                                 (spd_byte & 0x0F)));
> >                         if (dimm_speed >= glspeed) {
> > +                               casmap_shift = 1; /* -.5 is a shift of 1 */
> >                                 /* IF -1 timing is supported, check -1 timing > GeodeLink */
> >                                 spd_byte = spd_read_byte(DIMM0, SPD_SDRAM_CYCLE_TIME_3RD);
> >                                 if (spd_byte != 0) {
> >                                         /* Turn SPD ns time into MHZ. Check what the asm does to this math. */
> >                                         dimm_speed = 2 * (10000 / (((spd_byte >> 4) * 10) + (spd_byte & 0x0F)));
> > -                                       if (dimm_speed <= glspeed) {
> > -                                               /* set we can use -.5 timing but not -1 */
> > -                                               spd_byte = 31 - __builtin_clz((uint32_t) casmap0);
> > -                                               /* just want bits in the lower byte since we have to cast to a 32 */
> > -                                               casmap0 &= 0xFF << (--spd_byte);
> > +                                       if (dimm_speed >= glspeed) {
> > +                                               casmap_shift = 2; /* -1 is a shift of 2 */
> >                                         }
> > -                               }       /*MIN_CYCLE_10 !=0 */
> > +                               }       /* SPD_SDRAM_CYCLE_TIME_3RD (-1) !=0 */
> >                         } else {
> > -                               /* Timing_05 < GLspeed, can't use -.5 or -1 timing */
> > -                               spd_byte = 31 - __builtin_clz((uint32_t) casmap0);
> > -                               /* just want bits in the lower byte since we have to cast to a 32 */
> > -                               casmap0 &= 0xFF << (spd_byte);
> > +                               casmap_shift = 0;
> >                         }
> > -               }               /*MIN_CYCLE_05 !=0 */
> > +               }       /* SPD_SDRAM_CYCLE_TIME_2ND (-.5) !=0 */
> > +               /* set the casmap based on the shift to limit possible CAS settings */
> > +               spd_byte = 31 - __builtin_clz((uint32_t) casmap0);
> > +               /* just want bits in the lower byte since we have to cast to a 32 */
> > +               casmap0 &= 0xFF << (spd_byte - casmap_shift);
> >         } else {                /* No DIMM */
> >                 casmap0 = 0;
> >         }
> > @@ -278,25 +277,25 @@
> >                         /* Turn SPD ns time into MHZ. Check what the asm does to this math. */
> >                         dimm_speed = 2 * (10000 / (((spd_byte >> 4) * 10) + (spd_byte & 0x0F)));
> >                         if (dimm_speed >= glspeed) {
> > +                               casmap_shift = 1; /* -.5 is a shift of 1 */
> >                                 /* IF -1 timing is supported, check -1 timing > GeodeLink */
> >                                 spd_byte = spd_read_byte(DIMM1, SPD_SDRAM_CYCLE_TIME_3RD);
> >                                 if (spd_byte != 0) {
> >                                         /* Turn SPD ns time into MHZ. Check what the asm does to this math. */
> >                                         dimm_speed = 2 * (10000 / (((spd_byte >> 4) * 10) + (spd_byte & 0x0F)));
> > -                                       if (dimm_speed <= glspeed) {
> > -                                               /* set we can use -.5 timing but not -1 */
> > -                                               spd_byte = 31 - __builtin_clz((uint32_t) casmap1);
> > -                                               /* just want bits in the lower byte since we have to cast to a 32 */
> > -                                               casmap1 &= 0xFF << (--spd_byte);
> > +                                       if (dimm_speed >= glspeed) {
> > +                                               casmap_shift = 2; /* -1 is a shift of 2 */
> >                                         }
> > -                               }       /*MIN_CYCLE_10 !=0 */
> > +                                       /* note that the -1 result doesn't need to change the available CAS map */
> > +                               }       /* SPD_SDRAM_CYCLE_TIME_3RD (-1) !=0 */
> >                         } else {
> > -                               /* Timing_05 < GLspeed, can't use -.5 or -1 timing */
> > -                               spd_byte = 31 - __builtin_clz((uint32_t) casmap1);
> > -                               /* just want bits in the lower byte since we have to cast to a 32 */
> > -                               casmap1 &= 0xFF << (spd_byte);
> > +                               casmap_shift = 0;
> >                         }
> > -               }               /*MIN_CYCLE_05 !=0 */
> > +               }       /* SPD_SDRAM_CYCLE_TIME_2ND (-.5) !=0 */
> > +               /* set the casmap based on the shift to limit possible CAS settings */
> > +               spd_byte = 31 - __builtin_clz((uint32_t) casmap1);
> > +               /* just want bits in the lower byte since we have to cast to a 32 */
> > +               casmap1 &= 0xFF << (spd_byte - casmap_shift);
> >         } else {                /* No DIMM */
> >                 casmap1 = 0;
> >         }