Re: [PATCH v2 33/78] drm/bridge: dw-dp: Switch to atomic_create_state

[sashiko-bot@kernel.org]

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

Pre-existing issues:
- [High] Missing completion reinitialization in AUX transfer exposes driver to spurious immediate returns
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commit a0eb2a01158c71ba22ad17e3ef567be4fe4e603f
Author: Maxime Ripard <mripard@kernel.org>

drm/bridge: dw-dp: Switch to atomic_create_state

The commit replaces the deprecated atomic_reset callback and its helper
with atomic_create_state and its corresponding helper in the Synopsys
DW DP driver.

> diff --git a/drivers/gpu/drm/bridge/synopsys/dw-dp.c b/drivers/gpu/drm/bridge/synopsys/dw-dp.c
> index 21541be094c47..98437dc33d4db 100644
> --- a/drivers/gpu/drm/bridge/synopsys/dw-dp.c
> +++ b/drivers/gpu/drm/bridge/synopsys/dw-dp.c

[ ... ]

This isn't a bug introduced by this patch, but I noticed a pre-existing
issue while reviewing this file:

drivers/gpu/drm/bridge/synopsys/dw-dp.c:dw_dp_aux_transfer() {
    ...
	if (msg->size > 0)
		value = FIELD_PREP(AUX_LEN_REQ, msg->size - 1);
	else
		value = FIELD_PREP(I2C_ADDR_ONLY, 1);
	value |= FIELD_PREP(AUX_CMD_TYPE, msg->request);
	value |= FIELD_PREP(AUX_ADDR, msg->address);
	regmap_write(dp->regmap, DW_DP_AUX_CMD, value);

	status = wait_for_completion_timeout(&dp->complete, timeout);
    ...
}

[Severity: High]
Does this code need a call to reinit_completion() on dp->complete before
triggering the hardware transfer with regmap_write()?

If a previous transfer times out (leaving the completion count at 0) and
the interrupt handler fires later, complete() will increment the completion
counter to 1.

The very next call to dw_dp_aux_transfer() would consume this leftover
completion and immediately return success without actually waiting for the
new transaction to finish.

Could this cause the driver to read an incomplete hardware status or stale
data, leading to unpredictable AUX failures and display initialization errors?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260608-drm-no-more-bridge-reset-v2-0-0a91018bf886@kernel.org?part=33