[PATCH] drm/dsc: Return unsigned long on compute offset

[Cornij, Nikola]

If you're going to make all of them the same, then u64, please.

This is because I'm not sure if calculations require 64-bit at some stage.

-----Original Message-----
From: Lipski, Mikita <Mikita.Lipski at amd.com> 
Sent: November 19, 2019 10:08 AM
To: Ville Syrjälä <ville.syrjala at linux.intel.com>; Lipski, Mikita <Mikita.Lipski at amd.com>
Cc: amd-gfx at lists.freedesktop.org; dri-devel at lists.freedesktop.org; Cornij, Nikola <Nikola.Cornij at amd.com>
Subject: Re: [PATCH] drm/dsc: Return unsigned long on compute offset



On 19/11/2019 09:56, Ville Syrjälä wrote:
> On Tue, Nov 19, 2019 at 09:45:26AM -0500, mikita.lipski at amd.com wrote:
>> From: Mikita Lipski <mikita.lipski at amd.com>
>>
>> We shouldn't compare int with unsigned long to find the max value and 
>> since we are not expecting negative value returned from 
>> compute_offset we should make this function return unsigned long so 
>> we can compare the values when computing rc parameters.
> 
> Why are there other unsigned longs in dsc parameter computation in the 
> first place?

I believe it was initially set to be unsigned long for variable consistency, when we ported intel_compute_rc_parameters into drm_dsc_compute_rc_parameters. But now that I look at it, we can actually just set them to u32 or u64, as nothing should exceed that.
> 
>>
>> Cc: Nikola Cornij <nikola.cornij at amd.com>
>> Cc: Harry Wentland <harry.wentland at amd.com>
>> Signed-off-by: Mikita Lipski <mikita.lipski at amd.com>
>> ---
>>   drivers/gpu/drm/drm_dsc.c | 6 +++---
>>   1 file changed, 3 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/drm_dsc.c b/drivers/gpu/drm/drm_dsc.c
>> index 74f3527f567d..ec40604ab6a2 100644
>> --- a/drivers/gpu/drm/drm_dsc.c
>> +++ b/drivers/gpu/drm/drm_dsc.c
>> @@ -245,11 +245,11 @@ void drm_dsc_pps_payload_pack(struct drm_dsc_picture_parameter_set *pps_payload,
>>   }
>>   EXPORT_SYMBOL(drm_dsc_pps_payload_pack);
>>   
>> -static int compute_offset(struct drm_dsc_config *vdsc_cfg, int pixels_per_group,
>> +static unsigned long compute_offset(struct drm_dsc_config *vdsc_cfg, int pixels_per_group,
>>   				int groups_per_line, int grpcnt)
>>   {
>> -	int offset = 0;
>> -	int grpcnt_id = DIV_ROUND_UP(vdsc_cfg->initial_xmit_delay, pixels_per_group);
>> +	unsigned long offset = 0;
>> +	unsigned long grpcnt_id = DIV_ROUND_UP(vdsc_cfg->initial_xmit_delay, pixels_per_group);
>>   
>>   	if (grpcnt <= grpcnt_id)
>>   		offset = DIV_ROUND_UP(grpcnt * pixels_per_group * vdsc_cfg->bits_per_pixel, 16);
>> -- 
>> 2.17.1
>>
>> _______________________________________________
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>> dri-devel at lists.freedesktop.org
>> https://lists.freedesktop.org/mailman/listinfo/dri-devel
> 

-- 
Thanks,
Mikita Lipski
Software Engineer 2, AMD
mikita.lipski at amd.com