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

[Mikita Lipski]

On 19/11/2019 16:09, Mikita Lipski wrote:
> 
> 
> On 19/11/2019 12:11, Ville Syrjälä wrote:
>> On Tue, Nov 19, 2019 at 04:59:40PM +0000, Cornij, Nikola wrote:
>>> 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.
>>
>> If it does then it's already broken. Someone should probably figure out
>> what's actally needed instead of shooting ducks with an icbm.
>>


Sorry made a type below. Supposed to be "I don't think it is broken"

> I don't think it is not broken, cause I'm currently testing DSC.
> The patch I sent early simply fixes the error of comparing  signed and 
> unsigned variables.
> 
> We can then submit a second patch addressing the issue of using unsigned 
> long int instead of u32. Also, since the variables in drm_dsc_config 
> structure are all of type u8 and u16, the calculation values shouldn't 
> exceed the size of u32.
> 
> Thanks
> 
>>>
>>> -----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
>>>>>
>>>>> _______________________________________________
>>>>> dri-devel mailing list
>>>>> 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
>>
> 

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