Change in flashrom[master]: [RFC] udelay: Relax clock_gettime() resolution expectations

March 26, 2020

Nico Huber has uploaded this change for review. ( https://review.coreboot.org/c/flashrom/+/39864 )


Change subject: [RFC] udelay: Relax clock_gettime() resolution expectations
......................................................................

[RFC] udelay: Relax clock_gettime() resolution expectations

Only few programmers actually want to delay by a single microsecond. So
we can relax the expected mininum resolution by default and let indivi-
dual programmers override as needed.

UNTESTED

Change-Id: Ia24f5c8440b7cb8abcc5a1509443d0c41fd2c559
Signed-off-by: Nico Huber <nico.h@gmx.de>
---
M bitbang_spi.c
M cli_classic.c
M nicintel_eeprom.c
M udelay.c
4 files changed, 15 insertions(+), 7 deletions(-)



  git pull ssh://review.coreboot.org:29418/flashrom refs/changes/64/39864/1

diff --git a/bitbang_spi.c b/bitbang_spi.c
index 7c183c3..8e5b8f2 100644
--- a/bitbang_spi.c
+++ b/bitbang_spi.c
@@ -104,6 +104,8 @@
 	mst.data = master;
 	register_spi_master(&mst);
 
+	myusec_calibrate_delay(100);
+
 	/* Only mess with the bus if we're sure nobody else uses it. */
 	bitbang_spi_request_bus(master);
 	bitbang_spi_set_cs(master, 1);
diff --git a/cli_classic.c b/cli_classic.c
index 73cc417..2436351 100644
--- a/cli_classic.c
+++ b/cli_classic.c
@@ -454,7 +454,7 @@
 	}
 
 	/* FIXME: Delay calibration should happen in programmer code. */
-	myusec_calibrate_delay();
+	myusec_calibrate_delay(1000);
 
 	if (programmer_init(prog, pparam)) {
 		msg_perr("Error: Programmer initialization failed.\n");
diff --git a/nicintel_eeprom.c b/nicintel_eeprom.c
index 4d45f79..06284d4 100644
--- a/nicintel_eeprom.c
+++ b/nicintel_eeprom.c
@@ -449,6 +449,8 @@
 
 int nicintel_ee_init(void)
 {
+	myusec_calibrate_delay(100);
+
 	if (rget_io_perms())
 		return 1;
 
diff --git a/udelay.c b/udelay.c
index 6c0efc4..3f0b6d1 100644
--- a/udelay.c
+++ b/udelay.c
@@ -52,11 +52,11 @@
 	} while (now.tv_sec < end.tv_sec || (now.tv_sec == end.tv_sec && now.tv_nsec < end.tv_nsec));
 }
 
-static int clock_check_res(void)
+static int clock_check_res(const unsigned int resolution_ns)
 {
 	struct timespec res;
 	if (!clock_getres(clock_id, &res)) {
-		if (res.tv_sec == 0 && res.tv_nsec <= 100) {
+		if (res.tv_sec == 0 && res.tv_nsec <= resolution_ns) {
 			msg_pinfo("Using clock_gettime for delay loops (clk_id: %d, resolution: %ldns).\n",
 				  (int)clock_id, res.tv_nsec);
 			use_clock_gettime = true;
@@ -65,7 +65,7 @@
 	} else if (clock_id != CLOCK_REALTIME && errno == EINVAL) {
 		/* Try again with CLOCK_REALTIME. */
 		clock_id = CLOCK_REALTIME;
-		return clock_check_res();
+		return clock_check_res(resolution_ns);
 	}
 	return 0;
 }
@@ -77,7 +77,7 @@
 #endif /* HAVE_CLOCK_GETTIME == 1 */
 
 /* loops per microsecond */
-static unsigned long micro = 1;
+static unsigned long micro;
 
 __attribute__ ((noinline)) void myusec_delay(unsigned int usecs)
 {
@@ -133,15 +133,19 @@
 	return timeusec;
 }
 
-void myusec_calibrate_delay(void)
+void myusec_calibrate_delay(const unsigned int resolution_ns)
 {
-	if (clock_check_res())
+	if (clock_check_res(resolution_ns))
 		return;
 
+	if (micro)
+		return;	/* already calibrated */
+
 	unsigned long count = 1000;
 	unsigned long timeusec, resolution;
 	int i, tries = 0;
 
+	micro = 1;
 	msg_pinfo("Calibrating delay loop... ");
 	resolution = measure_os_delay_resolution();
 	if (resolution) {

-- 
To view, visit https://review.coreboot.org/c/flashrom/+/39864
To unsubscribe, or for help writing mail filters, visit https://review.coreboot.org/settings

Gerrit-Project: flashrom
Gerrit-Branch: master
Gerrit-Change-Id: Ia24f5c8440b7cb8abcc5a1509443d0c41fd2c559
Gerrit-Change-Number: 39864
Gerrit-PatchSet: 1
Gerrit-Owner: Nico Huber <nico.h@gmx.de>
Gerrit-MessageType: newchange

    

Nico Huber (Code Review)

Nico Huber (Code Review)

Nico Huber (Code Review)

tags

participants (1)