[Intel-gfx] [PATCH 2/2] drm/i915/guc: Allow for very slow GuC loading
John Harrison
john.c.harrison at intel.com
Sat Mar 11 01:01:42 UTC 2023
On 3/3/2023 11:20, Ceraolo Spurio, Daniele wrote:
> On 2/17/2023 3:47 PM, John.C.Harrison at Intel.com wrote:
>> From: John Harrison <John.C.Harrison at Intel.com>
>>
>> A failure to load the GuC is occasionally observed where the GuC log
>> actually showed that the GuC had loaded just fine. The implication
>> being that the load just took ever so slightly longer than the 200ms
>> timeout. Given that the actual time should be tens of milliseconds at
>> the slowest, this should never happen. So far the issue has generally
>> been caused by a bad IFWI resulting in low frequencies during boot
>> (depsite the KMD requesting max frequency). However, the issue seems
>> to happen more often than one would like.
>>
>> So a) increase the timeout so that the user still gets a working
>> system even in the case of slow load. And b) report the frequency
>> during the load to see if that is the case of the slow down.
>
> Some refs would be good here. From a quick search, these seems to match:
>
> https://gitlab.freedesktop.org/drm/intel/-/issues/7931
> https://gitlab.freedesktop.org/drm/intel/-/issues/8060
> https://gitlab.freedesktop.org/drm/intel/-/issues/8083
> https://gitlab.freedesktop.org/drm/intel/-/issues/8136
> https://gitlab.freedesktop.org/drm/intel/-/issues/8137
Should these have a prefix tag? If so, what? 'closes' is not entirely
accurate. This patch is just to help with debug of the underlying issue.
And if the timeout is reduced then it won't necessarily allow a slow
system to work. See below.
>
>>
>> Signed-off-by: John Harrison <John.C.Harrison at Intel.com>
>> ---
>> drivers/gpu/drm/i915/gt/uc/intel_guc_fw.c | 37 +++++++++++++++++++++--
>> 1 file changed, 34 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_fw.c
>> b/drivers/gpu/drm/i915/gt/uc/intel_guc_fw.c
>> index 2f5942606913d..72e003f50617d 100644
>> --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_fw.c
>> +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_fw.c
>> @@ -12,6 +12,7 @@
>> #include "gt/intel_gt.h"
>> #include "gt/intel_gt_mcr.h"
>> #include "gt/intel_gt_regs.h"
>> +#include "gt/intel_rps.h"
>> #include "intel_guc_fw.h"
>> #include "intel_guc_print.h"
>> #include "i915_drv.h"
>> @@ -139,9 +140,12 @@ static int guc_wait_ucode(struct intel_guc *guc)
>> {
>> struct intel_gt *gt = guc_to_gt(guc);
>> struct intel_uncore *uncore = gt->uncore;
>> + ktime_t before, after, delta;
>> bool success;
>> u32 status;
>> - int ret;
>> + int ret, count;
>> + u64 delta_ms;
>> + u32 before_freq;
>> /*
>> * Wait for the GuC to start up.
>> @@ -159,13 +163,32 @@ static int guc_wait_ucode(struct intel_guc *guc)
>> * issues to be resolved. In the meantime bump the timeout to
>> * 200ms. Even at slowest clock, this should be sufficient. And
>> * in the working case, a larger timeout makes no difference.
>> + *
>> + * IFWI updates have also been seen to cause sporadic failures
>> due to
>> + * the requested frequency not being granted and thus the firmware
>> + * load is attempted at minimum frequency. That can lead to load
>> times
>> + * in the seconds range. However, there is a limit on how long an
>> + * individual wait_for() can wait. So wrap it in a loop.
>> */
>> - ret = wait_for(guc_load_done(uncore, &status, &success), 200);
>> + before_freq = intel_rps_read_actual_frequency(&uncore->gt->rps);
>> + before = ktime_get();
>> + for (count = 0; count < 20; count++) {
>> + ret = wait_for(guc_load_done(uncore, &status, &success), 1000);
>
> Isn't 20 secs a bit too long for an in-place wait? I get that if the
> GuC doesn't load (or fail to) within a few secs the HW is likely
> toast, but still that seems a bit too long to me. What's the worst
> case load time ever observed? I suggest reducing the wait to 3 secs as
> a compromise, if that's bigger than the worst case.
I can drop it to 3 for normal builds and keep 20 for
CONFIG_DRM_I915_DEBUG_GEM builds. However, that won't actually be long
enough for all slow situations. We have seen times of at least 11s when
the GPU is running at minimum frequency. So, for CI runs we definitely
want to keep the 20s limit. For end users? Is it better to wait for up
to 20s or to boot in display only fallback mode? And note that this is a
timeout only. A functional system will still complete in tens of
milliseconds.
John.
>
> The patch LGTM apart from this point.
>
> Daniele
>
>> + if (!ret || !success)
>> + break;
>> +
>> + guc_dbg(guc, "load still in progress, count = %d, freq =
>> %dMHz\n",
>> + count, intel_rps_read_actual_frequency(&uncore->gt->rps));
>> + }
>> + after = ktime_get();
>> + delta = ktime_sub(after, before);
>> + delta_ms = ktime_to_ms(delta);
>> if (ret || !success) {
>> u32 ukernel = REG_FIELD_GET(GS_UKERNEL_MASK, status);
>> u32 bootrom = REG_FIELD_GET(GS_BOOTROM_MASK, status);
>> - guc_info(guc, "load failed: status = 0x%08X, ret = %d\n",
>> status, ret);
>> + guc_info(guc, "load failed: status = 0x%08X, time = %lldms,
>> freq = %dMHz, ret = %d\n",
>> + status, delta_ms,
>> intel_rps_read_actual_frequency(&uncore->gt->rps), ret);
>> guc_info(guc, "load failed: status: Reset = %d, BootROM =
>> 0x%02X, UKernel = 0x%02X, MIA = 0x%02X, Auth = 0x%02X\n",
>> REG_FIELD_GET(GS_MIA_IN_RESET, status),
>> bootrom, ukernel,
>> @@ -206,6 +229,14 @@ static int guc_wait_ucode(struct intel_guc *guc)
>> /* Uncommon/unexpected error, see earlier status code print
>> for details */
>> if (ret == 0)
>> ret = -ENXIO;
>> + } else if (delta_ms > 200) {
>> + guc_warn(guc, "excessive init time: %lldms! [freq = %dMHz,
>> before = %dMHz, status = 0x%08X, count = %d, ret = %d]\n",
>> + delta_ms,
>> intel_rps_read_actual_frequency(&uncore->gt->rps),
>> + before_freq, status, count, ret);
>> + } else {
>> + guc_dbg(guc, "init took %lldms, freq = %dMHz, before =
>> %dMHz, status = 0x%08X, count = %d, ret = %d\n",
>> + delta_ms,
>> intel_rps_read_actual_frequency(&uncore->gt->rps),
>> + before_freq, status, count, ret);
>> }
>> return ret;
>
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