On Wed, 15 Nov 2023 at 01:00, Jonathan Marek <[email protected]> wrote:
>
> Make it clear why the pkt_per_line value is being "divided by 2".
>
> Signed-off-by: Jonathan Marek <[email protected]>
> ---
> drivers/gpu/drm/msm/dsi/dsi_host.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/drivers/gpu/drm/msm/dsi/dsi_host.c b/drivers/gpu/drm/msm/dsi/dsi_host.c
> index 66f198e21a7e..842765063b1b 100644
> --- a/drivers/gpu/drm/msm/dsi/dsi_host.c
> +++ b/drivers/gpu/drm/msm/dsi/dsi_host.c
> @@ -877,6 +877,8 @@ static void dsi_update_dsc_timing(struct msm_dsi_host *msm_host, bool is_cmd_mod
> /* DSI_VIDEO_COMPRESSION_MODE & DSI_COMMAND_COMPRESSION_MODE
> * registers have similar offsets, so for below common code use
> * DSI_VIDEO_COMPRESSION_MODE_XXXX for setting bits
> + *
> + * pkt_per_line is log2 encoded, >>1 works for supported values (1,2,4)
> */
> reg |= DSI_VIDEO_COMPRESSION_MODE_CTRL_PKT_PER_LINE(pkt_per_line >> 1);
Should we switch to ffs() or fls() instead?
> reg |= DSI_VIDEO_COMPRESSION_MODE_CTRL_EOL_BYTE_NUM(eol_byte_num);
> --
> 2.26.1
>
--
With best wishes
Dmitry
On 11/15/23 2:38 AM, Dmitry Baryshkov wrote:
> On Wed, 15 Nov 2023 at 01:00, Jonathan Marek <[email protected]> wrote:
>>
>> Make it clear why the pkt_per_line value is being "divided by 2".
>>
>> Signed-off-by: Jonathan Marek <[email protected]>
>> ---
>> drivers/gpu/drm/msm/dsi/dsi_host.c | 2 ++
>> 1 file changed, 2 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/msm/dsi/dsi_host.c b/drivers/gpu/drm/msm/dsi/dsi_host.c
>> index 66f198e21a7e..842765063b1b 100644
>> --- a/drivers/gpu/drm/msm/dsi/dsi_host.c
>> +++ b/drivers/gpu/drm/msm/dsi/dsi_host.c
>> @@ -877,6 +877,8 @@ static void dsi_update_dsc_timing(struct msm_dsi_host *msm_host, bool is_cmd_mod
>> /* DSI_VIDEO_COMPRESSION_MODE & DSI_COMMAND_COMPRESSION_MODE
>> * registers have similar offsets, so for below common code use
>> * DSI_VIDEO_COMPRESSION_MODE_XXXX for setting bits
>> + *
>> + * pkt_per_line is log2 encoded, >>1 works for supported values (1,2,4)
>> */
>> reg |= DSI_VIDEO_COMPRESSION_MODE_CTRL_PKT_PER_LINE(pkt_per_line >> 1);
>
> Should we switch to ffs() or fls() instead?
>
Just a ffs() on its own can be confusing as well (without the
information that only powers of two are possible), I think like this is
better.
>> reg |= DSI_VIDEO_COMPRESSION_MODE_CTRL_EOL_BYTE_NUM(eol_byte_num);
>> --
>> 2.26.1
>>
>
>
On 16/11/2023 20:45, Jonathan Marek wrote:
> On 11/15/23 2:38 AM, Dmitry Baryshkov wrote:
>> On Wed, 15 Nov 2023 at 01:00, Jonathan Marek <[email protected]> wrote:
>>>
>>> Make it clear why the pkt_per_line value is being "divided by 2".
>>>
>>> Signed-off-by: Jonathan Marek <[email protected]>
>>> ---
>>> drivers/gpu/drm/msm/dsi/dsi_host.c | 2 ++
>>> 1 file changed, 2 insertions(+)
>>>
>>> diff --git a/drivers/gpu/drm/msm/dsi/dsi_host.c
>>> b/drivers/gpu/drm/msm/dsi/dsi_host.c
>>> index 66f198e21a7e..842765063b1b 100644
>>> --- a/drivers/gpu/drm/msm/dsi/dsi_host.c
>>> +++ b/drivers/gpu/drm/msm/dsi/dsi_host.c
>>> @@ -877,6 +877,8 @@ static void dsi_update_dsc_timing(struct
>>> msm_dsi_host *msm_host, bool is_cmd_mod
>>> /* DSI_VIDEO_COMPRESSION_MODE & DSI_COMMAND_COMPRESSION_MODE
>>> * registers have similar offsets, so for below common code use
>>> * DSI_VIDEO_COMPRESSION_MODE_XXXX for setting bits
>>> + *
>>> + * pkt_per_line is log2 encoded, >>1 works for supported
>>> values (1,2,4)
>>> */
>>> reg |=
>>> DSI_VIDEO_COMPRESSION_MODE_CTRL_PKT_PER_LINE(pkt_per_line >> 1);
>>
>> Should we switch to ffs() or fls() instead?
>>
>
> Just a ffs() on its own can be confusing as well (without the
> information that only powers of two are possible), I think like this is
> better.
Sounds fair. Could you please then add `if (pkt_per_line > 4)
drm_warn("pkt_per_line too big");`
With that in place:
Reviewed-by: Dmitry Baryshkov <[email protected]>
>
>>> reg |=
>>> DSI_VIDEO_COMPRESSION_MODE_CTRL_EOL_BYTE_NUM(eol_byte_num);
>>> --
>>> 2.26.1
>>>
>>
>>
--
With best wishes
Dmitry