Re: [PATCH v7 11/18] drm/rockchip: dw_dp: Implement out-of-band HPD handling

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] Missing runtime PM acquisition in out-of-band HPD callbacks leads to SError crashes once runtime PM is enabled.
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--- Patch [11]: [PATCH v7 11/18] drm/rockchip: dw_dp: Implement out-of-band HPD handling ---
commit 38a0d76cc721376e1ac94e73ba9bcc954b4597fd
Author: Sebastian Reichel <sebastian.reichel@collabora.com>

drm/rockchip: dw_dp: Implement out-of-band HPD handling

This patch implements out-of-band hotplug handling to receive external hotplug
information from the USB-C state machine. This moves the logic from the USBDP
PHY driver to avoid SError crashes once runtime PM is enabled.

> diff --git a/drivers/gpu/drm/rockchip/dw_dp-rockchip.c b/drivers/gpu/drm/rockchip/dw_dp-rockchip.c
> index 005938dc66c9f..b2e817044c942 100644
> --- a/drivers/gpu/drm/rockchip/dw_dp-rockchip.c
> +++ b/drivers/gpu/drm/rockchip/dw_dp-rockchip.c

[ ... ]

> +static void dw_dp_rockchip_hpd_sw_sel(void *data, bool force_hpd_from_sw)
> +{
> +	struct rockchip_dw_dp *dp = data;
> +	u32 hpd_reg = dp->pdata->hpd_reg[dp->id];
> +
> +	dp->hpd_sel = force_hpd_from_sw;
> +
> +	regmap_write(dp->vo_grf, hpd_reg,
> +		     FIELD_PREP_WM16(ROCKCHIP_VO_GRF_DP_SINK_HPD_SEL, dp->hpd_sel));

[Severity: Medium]
Will this regmap_write() trigger an SError if the USB-C state machine
triggers an out-of-band hotplug event while the DP controller is runtime
suspended?

The commit message notes this patch is intended to prevent SError problems
once runtime PM is enabled. Since the register access requires the DP
controller's power domain, should there be a runtime PM acquisition before
writing to the vo_grf regmap?

> +}
> +
> +static void dw_dp_rockchip_hpd_sw_cfg(void *data, bool hpd)
> +{
> +	struct rockchip_dw_dp *dp = data;
> +	u32 hpd_reg = dp->pdata->hpd_reg[dp->id];
> +
> +	dev_dbg(dp->dev, "Force HPD connected=%s\n", str_yes_no(hpd));
> +
> +	dp->hpd_cfg = hpd;
> +
> +	regmap_write(dp->vo_grf, hpd_reg,
> +		     FIELD_PREP_WM16(ROCKCHIP_VO_GRF_DP_SINK_HPD_CFG, dp->hpd_cfg));

[Severity: Medium]
Similarly, could this asynchronous write cause an SError crash if it fires
without first ensuring the DP controller's power domain is active via runtime
PM?

> +}

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Sashiko AI review · https://sashiko.dev/#/patchset/20260728-synopsys-dw-dp-improvements-v7-0-b7640fa8cf48@collabora.com?part=11