Re: [PATCH 07/13] drm/sun4i: hdmi: Don't leak sync polarity bits into packet control

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:

Pre-existing issues:
- [High] Encoder atomic enable callback calls functions that can sleep.
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--- Patch [7]: [PATCH 07/13] drm/sun4i: hdmi: Don't leak sync polarity bits into packet control ---
commit 65d502c65ade8ff425b6b395888cc0a59bbbb7c3
Author: Jernej Skrabec <jernej.skrabec@gmail.com>

drm/sun4i: hdmi: Don't leak sync polarity bits into packet control

This commit fixes an issue where stale sync polarity bits were ORed into the
packet control register. It replaces the OR assignment with a direct
assignment to prevent selecting incorrect packet types.

> diff --git a/drivers/gpu/drm/sun4i/sun4i_hdmi_enc.c b/drivers/gpu/drm/sun4i/sun4i_hdmi_enc.c
> index e99f52ebb26f0..97253d631b2bd 100644
> --- a/drivers/gpu/drm/sun4i/sun4i_hdmi_enc.c
> +++ b/drivers/gpu/drm/sun4i/sun4i_hdmi_enc.c
> @@ -160,7 +160,7 @@ static void sun4i_hdmi_enable(struct drm_encoder *encoder,
>  
>  	drm_atomic_helper_connector_hdmi_update_infoframes(connector, state);

[Severity: High]
This isn't a bug introduced by this patch, but does this code sleep in an
atomic context?

The sun4i_hdmi_enable() function is registered as an encoder atomic enable
callback, which executes in an atomic context during non-blocking commits.
However, it calls drm_atomic_helper_connector_hdmi_update_infoframes() here,
which explicitly acquires a mutex. It also calls clk_prepare_enable() just
above this snippet, which can sleep.

Could calling these sleeping functions during atomic commit paths cause
kernel warnings or potential deadlocks?

> -	val |= SUN4I_HDMI_PKT_CTRL_TYPE(0, SUN4I_HDMI_PKT_AVI);
> +	val = SUN4I_HDMI_PKT_CTRL_TYPE(0, SUN4I_HDMI_PKT_AVI);
>  	val |= SUN4I_HDMI_PKT_CTRL_TYPE(1, SUN4I_HDMI_PKT_END);
>  	writel(val, hdmi->base + SUN4I_HDMI_PKT_CTRL_REG(0));
>

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Sashiko AI review · https://sashiko.dev/#/patchset/cover.1785772659.git.jernej.skrabec@gmail.com?part=7