On 11/13/25 9:29 PM, Chris Morgan wrote:
> From: Chris Morgan <[email protected]>
>
> Add support for the dw-hdmi-qp driver to handle devices with missing
> HPD pins.
>
> Since in this situation we are now polling for the EDID data via i2c
> change the error message to a debug message when we are unable to
> complete an i2c read, as a disconnected device would otherwise fill
> dmesg with i2c read errors.
>
> Signed-off-by: Chris Morgan <[email protected]>
> ---
> drivers/gpu/drm/bridge/synopsys/dw-hdmi-qp.c | 32 +++++++++++++++++---
> 1 file changed, 28 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/bridge/synopsys/dw-hdmi-qp.c
> b/drivers/gpu/drm/bridge/synopsys/dw-hdmi-qp.c
> index 39332c57f2c5..a2b1a4821714 100644
> --- a/drivers/gpu/drm/bridge/synopsys/dw-hdmi-qp.c
> +++ b/drivers/gpu/drm/bridge/synopsys/dw-hdmi-qp.c
> @@ -145,6 +145,7 @@ struct dw_hdmi_qp {
> struct regmap *regm;
>
> unsigned long tmds_char_rate;
> + bool no_hpd;
> };
>
> static void dw_hdmi_qp_write(struct dw_hdmi_qp *hdmi, unsigned int val,
> @@ -520,6 +521,11 @@ static int dw_hdmi_qp_i2c_read(struct dw_hdmi_qp *hdmi,
> i2c->is_regaddr = true;
> }
>
> + /*
> + * Mark errors as debug messages when using no_hpd so no device
> + * attached does not fill up dmesg.
> + */
> +
Using the *_ratelimited() variant - see below - would make this comment kind of
redundant. Moreover, you've already explained the rationale behind the change
in the commit description. Hence I'd rather drop it.
> while (length--) {
> reinit_completion(&i2c->cmp);
>
> @@ -535,14 +541,20 @@ static int dw_hdmi_qp_i2c_read(struct dw_hdmi_qp *hdmi,
>
> stat = wait_for_completion_timeout(&i2c->cmp, HZ / 10);
> if (!stat) {
> - dev_err(hdmi->dev, "i2c read timed out\n");
> + if (hdmi->no_hpd)
> + dev_dbg(hdmi->dev, "i2c read timed out\n");
I think it's worth switching to dev_dbg_ratelimited() in this case.
> + else
> + dev_err(hdmi->dev, "i2c read timed out\n");
> dw_hdmi_qp_write(hdmi, 0x01, I2CM_CONTROL0);
> return -EAGAIN;
> }
>
> /* Check for error condition on the bus */
> if (i2c->stat & I2CM_NACK_RCVD_IRQ) {
> - dev_err(hdmi->dev, "i2c read error\n");
> + if (hdmi->no_hpd)
> + dev_dbg(hdmi->dev, "i2c read error\n");
Same here.
> + else
> + dev_err(hdmi->dev, "i2c read error\n");
> dw_hdmi_qp_write(hdmi, 0x01, I2CM_CONTROL0);
> return -EIO;
> }
[...]
Regardless,
Reviewed-by: Cristian Ciocaltea <[email protected]>
