Re: [Intel-gfx] [PATCH] drm/i915/guc/slpc: Apply min softlimit correctly
On Fri, 09 Jun 2023 15:02:52 -0700, Vinay Belgaumkar wrote:
>
Hi Vinay,
> We were skipping when min_softlimit was equal to RPn. We need to apply
> it rergardless as efficient frequency will push the SLPC min to RPe.
regardless
> This will break scenarios where user sets a min softlimit < RPe before
> reset and then performs a GT reset.
Can you explain the reason for the patch clearly in terms of variables in
the code, what variable has what value and what is the bug. I am not
following from the above description.
Thanks.
--
Ashutosh
>
> Fixes: 95ccf312a1e4 ("drm/i915/guc/slpc: Allow SLPC to use efficient
> frequency")
>
> Signed-off-by: Vinay Belgaumkar
> ---
> drivers/gpu/drm/i915/gt/uc/intel_guc_slpc.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_slpc.c
> b/drivers/gpu/drm/i915/gt/uc/intel_guc_slpc.c
> index 01b75529311c..ee9f83af7cf6 100644
> --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_slpc.c
> +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_slpc.c
> @@ -606,7 +606,7 @@ static int slpc_set_softlimits(struct intel_guc_slpc
> *slpc)
> if (unlikely(ret))
> return ret;
> slpc_to_gt(slpc)->defaults.min_freq = slpc->min_freq_softlimit;
> - } else if (slpc->min_freq_softlimit != slpc->min_freq) {
> + } else {
> return intel_guc_slpc_set_min_freq(slpc,
> slpc->min_freq_softlimit);
> }
> --
> 2.38.1
>
Re: [Intel-gfx] [PATCH] drm/i915/guc/slpc: Apply min softlimit correctly
On 6/13/2023 7:25 PM, Dixit, Ashutosh wrote:
On Fri, 09 Jun 2023 15:02:52 -0700, Vinay Belgaumkar wrote:
Hi Vinay,
We were skipping when min_softlimit was equal to RPn. We need to apply
it rergardless as efficient frequency will push the SLPC min to RPe.
regardless
This will break scenarios where user sets a min softlimit < RPe before
reset and then performs a GT reset.
Can you explain the reason for the patch clearly in terms of variables in
the code, what variable has what value and what is the bug. I am not
following from the above description.
Hi Ashutosh,
Scenario being fixed here is exactly the one in i915_pm_freq_api
reset/suspend subtests (currently in review). Test sets min freq to RPn
and then performs a reset. It then checks if cur_freq is RPn.
Here's the sequence that shows the problem-
RPLS:/home/gta# modprobe i915
RPLS:/home/gta# echo 1 > /sys/class/drm/card0/gt/gt0/slpc_ignore_eff_freq
RPLS:/home/gta# echo 300 > /sys/class/drm/card0/gt_min_freq_mhz (RPn)
RPLS:/home/gta# cat /sys/class/drm/card0/gt_cur_freq_mhz --> cur == RPn
as expected
300
RPLS:/home/gta# echo 1 > /sys/kernel/debug/dri/0/gt0/reset --> reset
RPLS:/home/gta# cat /sys/class/drm/card0/gt_min_freq_mhz --> shows the
internal cached variable correctly
300
RPLS:/home/gta# cat /sys/class/drm/card0/gt_cur_freq_mhz --> actual freq
being requested by SLPC (it's not RPn!!)
700
We need to sync up driver min freq value and SLPC min after a
reset/suspend. Currently, we skip if the user had manually set min to
RPn (this was an optimization we had before we enabled efficient freq
usage).
Thanks,
Vinay.
Thanks.
--
Ashutosh
Fixes: 95ccf312a1e4 ("drm/i915/guc/slpc: Allow SLPC to use efficient frequency")
Signed-off-by: Vinay Belgaumkar
---
drivers/gpu/drm/i915/gt/uc/intel_guc_slpc.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_slpc.c
b/drivers/gpu/drm/i915/gt/uc/intel_guc_slpc.c
index 01b75529311c..ee9f83af7cf6 100644
--- a/drivers/gpu/drm/i915/gt/uc/intel_guc_slpc.c
+++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_slpc.c
@@ -606,7 +606,7 @@ static int slpc_set_softlimits(struct intel_guc_slpc *slpc)
if (unlikely(ret))
return ret;
slpc_to_gt(slpc)->defaults.min_freq = slpc->min_freq_softlimit;
- } else if (slpc->min_freq_softlimit != slpc->min_freq) {
+ } else {
return intel_guc_slpc_set_min_freq(slpc,
slpc->min_freq_softlimit);
}
--
2.38.1
Re: [Intel-gfx] [PATCH] drm/i915/guc/slpc: Apply min softlimit correctly
On Fri, 09 Jun 2023 15:02:52 -0700, Vinay Belgaumkar wrote:
>
Hi Vinay,
> We were skipping when min_softlimit was equal to RPn. We need to apply
> it rergardless as efficient frequency will push the SLPC min to RPe.
> This will break scenarios where user sets a min softlimit < RPe before
> reset and then performs a GT reset.
>
> Fixes: 95ccf312a1e4 ("drm/i915/guc/slpc: Allow SLPC to use efficient
> frequency")
>
> Signed-off-by: Vinay Belgaumkar
> ---
> drivers/gpu/drm/i915/gt/uc/intel_guc_slpc.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_slpc.c
> b/drivers/gpu/drm/i915/gt/uc/intel_guc_slpc.c
> index 01b75529311c..ee9f83af7cf6 100644
> --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_slpc.c
> +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_slpc.c
> @@ -606,7 +606,7 @@ static int slpc_set_softlimits(struct intel_guc_slpc
> *slpc)
> if (unlikely(ret))
> return ret;
> slpc_to_gt(slpc)->defaults.min_freq = slpc->min_freq_softlimit;
> - } else if (slpc->min_freq_softlimit != slpc->min_freq) {
> + } else {
> return intel_guc_slpc_set_min_freq(slpc,
> slpc->min_freq_softlimit);
IMO the current code is unnecessarily complicated and confusing and similar
changes (with a little tweaking) should be made for max_freq too. But at
least this is a step in the right direction so:
Reviewed-by: Ashutosh Dixit
> }
> --
> 2.38.1
>
