[Intel-gfx] [PATCH v2] drm/i915/skl: Increase ddb blocks to support large cursor sizes

[Kumar, Shobhit]

On 12/19/2015 08:14 AM, Matt Roper wrote:
> On Fri, Dec 18, 2015 at 03:58:52PM -0800, Radhakrishna Sripada wrote:
>> Original value of 32 blocks is not sufficient when using cursor size of
>> 256x256 causing FIFO underruns when the reworked wm
>> caluclations in
>>
>> commit 024c9045221fe45482863c47c4b4c47d37f97cbf
>> Author: Matt Roper <matthew.d.roper at intel.com>
>> Date:   Thu Sep 24 15:53:11 2015 -0700
>>
>>      drm/i915/skl: Eliminate usage of pipe_wm_parameters from SKL-style WM (v4)
>>
>> are used. Increasing the number of blocks to 52 to make cursor plane tolerate
>> SAGV block time for the maximum possible cursor size.
>>
>> v2: Included Matt's suggestion, bumping up the no of blocks in multi-pipe case
>> to 16.
>>
>> Signed-off-by: Radhakrishna Sripada <radhakrishna.sripada at intel.com>
>> Signed-off-by: Kalyan Kondapally <kalyan.kondapally at intel.com>
>
> Can you try my patch "drm/i915/skl: Use proper plane dimensions for DDB
> and WM calculations" first and see if it solves your problems?  It's

Where can I find this patch ? Couldn't find in drm-intel branches or the 
mailing list.

Regards
Shobhit

> possible that your problems were caused by my fumble that I'm fixing
> with that patch; if that patch fixes the problem, then we may not need
> to alter the cursor's fixed allocation after all.
>
> Of course as we noted, there are a handful of new workarounds in the
> bspec (SAGV disabling, system memory bandwidth checking, etc.) that we
> still don't have in our driver yet, so if any of those are the true root
> cause, then your patch here is probably a reasonable short-term fix
> until we can take action on the new workarounds.  In that case, you can
> consider this patch
>
> Acknowledged-by: Matt Roper <matthew.d.roper at intel.com>
>
> Unfortunately I only have a BXT which doesn't exhibit the problems
> you're seeing, so I can't actually test this out myself.
>
>
> Matt
>
>> ---
>>   drivers/gpu/drm/i915/intel_pm.c | 4 ++--
>>   1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
>> index d385d99..c5ba4e5 100644
>> --- a/drivers/gpu/drm/i915/intel_pm.c
>> +++ b/drivers/gpu/drm/i915/intel_pm.c
>> @@ -2802,9 +2802,9 @@ skl_ddb_get_pipe_allocation_limits(struct drm_device *dev,
>>   static unsigned int skl_cursor_allocation(const struct intel_wm_config *config)
>>   {
>>   	if (config->num_pipes_active == 1)
>> -		return 32;
>> +		return 52;
>>
>> -	return 8;
>> +	return 16;
>>   }
>>
>>   static void skl_ddb_entry_init_from_hw(struct skl_ddb_entry *entry, u32 reg)
>> --
>> 1.9.1
>>
>