Re: [PATCH v2 4/6] drm/msm/dsi: add a comment to explain pkt_per_line encoding

Dmitry Baryshkov
2023-11-15T07:38:39Z

On Wed, 15 Nov 2023 at 01:00, Jonathan Marek <jonathan@marek.ca> wrote:
>
> Make it clear why the pkt_per_line value is being "divided by 2".
>
> Signed-off-by: Jonathan Marek <jonathan@marek.ca>
> ---
> 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