Re: [SeaBIOS] [PATCH 6/6] Use timer_check() instead of using floppy_motor_counter in BDA for the timeout check in floppy_wait_irq()

[Nikolay Nikolov]

This is the same as patch 7 from the previous series, except it also
removes the line "SET_BDA(floppy_motor_counter, FLOPPY_MOTOR_TICKS);"
from floppy_enable_controller().

Nikolay

On Sun, 2018-02-04 at 17:27 +0200, Nikolay Nikolov wrote:
> The problem with using floppy_motor_counter was that, after it
> reaches 0,
> it immediately stops the floppy motors, which is not what is supposed
> to
> happen on real hardware. Instead, after a timeout (like in the end of
> every floppy operation, regardless of the result - success, timeout
> or
> error), the floppy motors must be kept spinning for additional 2
> seconds
> (the FLOPPY_MOTOR_TICKS). So, now the floppy_motor_counter is
> initialized
> to 255 (the max value) in the beginning of the floppy operation (in
> floppy_turn_on_motor()). For IRQ timeouts, a different timeout is
> used,
> specified by the new FLOPPY_IRQ_TIMEOUT constant (currently set to 5
> seconds - a fairly conservative value, but should work reliably on
> most
> floppies).
>
> After the floppy operation, floppy_turn_off_motor_delayed() resets
> the
> floppy_motor_counter to 2 seconds (FLOPPY_MOTOR_TICKS).
>
> This is also consistent with what other PC BIOSes do.
> Signed-off-by: Nikolay Nikolov
>
> src/hw/floppy.c | 9 +++++----
>  1 file changed, 5 insertions(+), 4 deletions(-)
>
> diff --git a/src/hw/floppy.c b/src/hw/floppy.c
> index 77dbade..3012b3a 100644
> --- a/src/hw/floppy.c
> +++ b/src/hw/floppy.c
> @@ -34,6 +34,7 @@
>  #define FLOPPY_GAPLEN 0x1B
>  #define FLOPPY_FORMAT_GAPLEN 0x6c
>  #define FLOPPY_PIO_TIMEOUT 1000
> +#define FLOPPY_IRQ_TIMEOUT 5000
>
> #define FLOPPY_DOR_MOTOR_D     0x80 // Set to turn drive 3's motor
> ON
>  #define FLOPPY_DOR_MOTOR_C     0x40 // Set to turn drive 2's motor
> ON
> @@ -221,8 +222,9 @@ floppy_wait_irq(void)
>  {
>      u8 frs = GET_BDA(floppy_recalibration_status);
>      SET_BDA(floppy_recalibration_status, frs & ~FRS_IRQ);
> u32 end = timer_calc(FLOPPY_IRQ_TIMEOUT);
> for (;;) {
>    if (!GET_BDA(floppy_motor_counter)) {
>    if (timer_check(end)) {
>        warn_timeout();
>        floppy_disable_controller();
>        return DISK_RET_ETIMEOUT;
>
> @@ -324,7 +326,6 @@ static int
>  floppy_enable_controller(void)
>  {
>      dprintf(2, "Floppy_enable_controller\n");
> SET_BDA(floppy_motor_counter, FLOPPY_MOTOR_TICKS);
> // Clear the reset bit (enter reset state), but set 'enable IRQ
>
> and DMA'
>      floppy_dor_mask(FLOPPY_DOR_RESET, FLOPPY_DOR_IRQ);
>      // Set the reset bit (normal operation) and keep 'enable IRQ and
> DMA' on
> @@ -348,8 +349,8 @@ floppy_drive_pio(u8 floppyid, int command, u8
> *param)
>              return ret;
>      }
> // reset the disk motor timeout value of INT 08
> SET_BDA(floppy_motor_counter, FLOPPY_MOTOR_TICKS);
> // set the disk motor timeout value of INT 08 to the highest
>
> value
>
> SET_BDA(floppy_motor_counter, 255);
>
> // Turn on motor of selected drive, DMA & int enabled, normal
>
> operation
>      floppy_dor_write((floppyid ? FLOPPY_DOR_MOTOR_B :
> FLOPPY_DOR_MOTOR_A) | FLOPPY_DOR_IRQ | FLOPPY_DOR_RESET | floppyid);