[PATCH] drm/panfrost: Add errata descriptions from kbase

[Steven Price]

On 06/08/2019 22:08, Rob Herring wrote:
> On Tue, Aug 6, 2019 at 2:25 PM Alyssa Rosenzweig
> <alyssa.rosenzweig at collabora.com> wrote:
>>
>> While newer kbase include only the numbers of errata, older kbase
>> releases included one-line descriptions for each errata, which is useful
>> for those working on the driver. Import these descriptions. Most are
>> from kbase verbatim; a few I edited for clarity.
>>
>> A few issues pertaining to newer models are unknown as they were not
>> added to kbase until after kbase began stripping these comments.
>>
>> Signed-off-by: Alyssa Rosenzweig <alyssa.rosenzweig at collabora.com>
>> ---
>>   drivers/gpu/drm/panfrost/panfrost_issues.h | 80 ++++++++++++++++++++++
>>   1 file changed, 80 insertions(+)
> 
> A couple of nits below.
> 
[...]
>> +
>> +       /* TODO: Unknown */
> 
> This is Bifrost errata which is newer and I'm assuming will never have
> a description. Is there much point in any comment?

We could easily provide better comments for some of these. For example 
TMIX_8463 operates this code[1]:
> 	if (kbase_hw_has_issue(kbdev, BASE_HW_ISSUE_TMIX_8463)) {
> 		/* Ensure that L2 is not transitioning when we send the reset
> 		 * command */
> 		while (--max_loops && kbase_pm_get_trans_cores(kbdev,
> 				KBASE_PM_CORE_L2))
> 			;
> 
> 		WARN(!max_loops, "L2 power transition timed out while trying to reset\n");
> 	}
> 

So we can at least comment that the "L2 must not be transitioning when 
issuing reset command".

[1] 
https://gitlab.freedesktop.org/panfrost/mali_kbase/blob/master/driver/product/kernel/drivers/gpu/arm/midgard/backend/gpu/mali_kbase_jm_hw.c#L1197


I agree though that there's little point in "TODO: Unknown" comments.

Steve

>>          HW_ISSUE_TMIX_8463,
>> +
>> +       /* TODO: Unknown */
>>          GPUCORE_1619,
>> +
>> +       /* TODO: Unknown */
>>          HW_ISSUE_TMIX_8438,
>> +
>> +       /* TODO: Unknown */
>>          HW_ISSUE_TGOX_R1_1234,
>> +
>>          HW_ISSUE_END
>>   };
>>
>> --
>> 2.20.1
>>
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