Thank you for your contribution! Sashiko AI review found 1 potential issue(s) 
to consider:
- [Medium] Strict inequality check for maximum lane bit rate incorrectly 
rejects exact boundary values, causing valid display modes to fail.
--

--- Patch [1]: [PATCH v4 1/3] drm/rockchip: dsi: Add maximum per lane bit rate 
calculation ---
commit c849fa328462e27e823555ae008f52416cbc0bb9
Author: Chaoyi Chen <[email protected]>

drm/rockchip: dsi: Add maximum per lane bit rate calculation

This commit introduces chip-specific maximum lane bit rate boundaries for the
Rockchip DW MIPI DSI driver. This allows varying maximums per platform rather
than using a hardcoded 1500 Mbps default.

> diff --git a/drivers/gpu/drm/rockchip/dw-mipi-dsi-rockchip.c 
> b/drivers/gpu/drm/rockchip/dw-mipi-dsi-rockchip.c
> index 268d4993a04fd..fd91343d0f6d5 100644
> --- a/drivers/gpu/drm/rockchip/dw-mipi-dsi-rockchip.c
> +++ b/drivers/gpu/drm/rockchip/dw-mipi-dsi-rockchip.c

[ ... ]

> @@ -572,6 +573,7 @@ dw_mipi_dsi_get_lane_mbps(void *priv_data, const struct 
> drm_display_mode *mode,
>       unsigned long _fbdiv, best_fbdiv;
>       unsigned long min_delta = ULONG_MAX;
>  
> +     max_mbps = dsi->cdata->max_bit_rate_per_lane / USEC_PER_SEC;

[Severity: Medium]
Will this cause display modes that exactly match the new lower max_mbps
to fail?

In dw_mipi_dsi_get_lane_mbps(), there is a strict inequality check shortly
after this assignment:

        /* take 1 / 0.9, since mbps must big than bandwidth of RGB */
        tmp = DIV_ROUND_UP(mpclk * bpp * 10, lanes * 9);
        if (tmp < max_mbps)
                target_mbps = tmp;
        else
                DRM_DEV_ERROR(dsi->dev, "DPHY clock frequency is out of 
range\n");

Because this patch lowers the boundary to 1000 Mbps or 1200 Mbps for several
chips, display modes that yield a bandwidth exactly matching the chip's
maximum will now be rejected.

For example, a mode needing exactly 1000 Mbps would have previously passed
because 1000 < 1500, but will now fail since 1000 is not < 1000. Should the
check be updated to allow exact boundary values by using <= max_mbps?

-- 
Sashiko AI review ยท 
https://sashiko.dev/#/patchset/[email protected]?part=1

Reply via email to