diff options
Diffstat (limited to 'target/linux/bcm27xx/patches-5.4/950-0479-drm-v3d-Replace-wait_for-macros-to-remove-use-of-msl.patch')
| -rw-r--r-- | target/linux/bcm27xx/patches-5.4/950-0479-drm-v3d-Replace-wait_for-macros-to-remove-use-of-msl.patch | 89 |
1 files changed, 89 insertions, 0 deletions
diff --git a/target/linux/bcm27xx/patches-5.4/950-0479-drm-v3d-Replace-wait_for-macros-to-remove-use-of-msl.patch b/target/linux/bcm27xx/patches-5.4/950-0479-drm-v3d-Replace-wait_for-macros-to-remove-use-of-msl.patch new file mode 100644 index 0000000000..830bc1125e --- /dev/null +++ b/target/linux/bcm27xx/patches-5.4/950-0479-drm-v3d-Replace-wait_for-macros-to-remove-use-of-msl.patch @@ -0,0 +1,89 @@ +From 12b60ef71cc005ee7290f692169d46a7e78df01a Mon Sep 17 00:00:00 2001 +From: Yukimasa Sugizaki <4298265+Terminus-IMRC@users.noreply.github.com> +Date: Fri, 20 Mar 2020 19:01:23 +0900 +Subject: [PATCH] drm/v3d: Replace wait_for macros to remove use of + msleep (#3510) + +commit 9daee6141cc9c75b09659b02b1cb9eeb2f5e16cc upstream. + +The wait_for macro's for Broadcom V3D driver used msleep, which is +inappropriate due to its inaccuracy at low values (minimum wait time +is about 30ms on the Raspberry Pi). This sleep was triggering in +v3d_clean_caches(), causing us to only be able to dispatch ~33 compute +jobs per second. + +This patch replaces the macro with the one from the Intel i915 version +which uses usleep_range to provide more accurate waits. + +v2: Split from the vc4 patch so that we can confidently apply to + stable (by anholt) + +Signed-off-by: James Hughes <james.hughes@raspberrypi.com> +Signed-off-by: Eric Anholt <eric@anholt.net> +Link: https://patchwork.freedesktop.org/patch/msgid/20200217153145.13780-1-james.hughes@raspberrypi.com +Link: https://github.com/raspberrypi/linux/issues/3460 +Fixes: 57692c94dcbe ("drm/v3d: Introduce a new DRM driver for Broadcom V3D V3.x+") + +Co-authored-by: James Hughes <james.hughes@raspberrypi.com> +--- + drivers/gpu/drm/v3d/v3d_drv.h | 41 ++++++++++++++++++++++++----------- + 1 file changed, 28 insertions(+), 13 deletions(-) + +--- a/drivers/gpu/drm/v3d/v3d_drv.h ++++ b/drivers/gpu/drm/v3d/v3d_drv.h +@@ -260,27 +260,42 @@ struct v3d_csd_job { + }; + + /** +- * _wait_for - magic (register) wait macro ++ * __wait_for - magic wait macro + * +- * Does the right thing for modeset paths when run under kdgb or similar atomic +- * contexts. Note that it's important that we check the condition again after +- * having timed out, since the timeout could be due to preemption or similar and +- * we've never had a chance to check the condition before the timeout. ++ * Macro to help avoid open coding check/wait/timeout patterns. Note that it's ++ * important that we check the condition again after having timed out, since the ++ * timeout could be due to preemption or similar and we've never had a chance to ++ * check the condition before the timeout. + */ +-#define wait_for(COND, MS) ({ \ +- unsigned long timeout__ = jiffies + msecs_to_jiffies(MS) + 1; \ +- int ret__ = 0; \ +- while (!(COND)) { \ +- if (time_after(jiffies, timeout__)) { \ +- if (!(COND)) \ +- ret__ = -ETIMEDOUT; \ ++#define __wait_for(OP, COND, US, Wmin, Wmax) ({ \ ++ const ktime_t end__ = ktime_add_ns(ktime_get_raw(), 1000ll * (US)); \ ++ long wait__ = (Wmin); /* recommended min for usleep is 10 us */ \ ++ int ret__; \ ++ might_sleep(); \ ++ for (;;) { \ ++ const bool expired__ = ktime_after(ktime_get_raw(), end__); \ ++ OP; \ ++ /* Guarantee COND check prior to timeout */ \ ++ barrier(); \ ++ if (COND) { \ ++ ret__ = 0; \ + break; \ + } \ +- msleep(1); \ ++ if (expired__) { \ ++ ret__ = -ETIMEDOUT; \ ++ break; \ ++ } \ ++ usleep_range(wait__, wait__ * 2); \ ++ if (wait__ < (Wmax)) \ ++ wait__ <<= 1; \ + } \ + ret__; \ + }) + ++#define _wait_for(COND, US, Wmin, Wmax) __wait_for(, (COND), (US), (Wmin), \ ++ (Wmax)) ++#define wait_for(COND, MS) _wait_for((COND), (MS) * 1000, 10, 1000) ++ + static inline unsigned long nsecs_to_jiffies_timeout(const u64 n) + { + /* nsecs_to_jiffies64() does not guard against overflow */ |