[PATCH 13/14] drm/bridge: analogix_dp: only read AUX status when an error occured

[Robert Foss]

On Fri, May 3, 2024 at 5:13 PM Lucas Stach <l.stach at pengutronix.de> wrote:
>
> All AUX error responses raise the AUX_ERR interrupt, so there is no
> need to read the AUX status register in normal operation. Only read
> the status when an error occured and we can expect a different status
> than OK.
>
> Signed-off-by: Lucas Stach <l.stach at pengutronix.de>
> ---
>  drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c | 9 +++++----
>  1 file changed, 5 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c b/drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c
> index 143a78b1d156..0f016dca9f3d 100644
> --- a/drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c
> +++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c
> @@ -924,7 +924,6 @@ ssize_t analogix_dp_transfer(struct analogix_dp_device *dp,
>                              struct drm_dp_aux_msg *msg)
>  {
>         u32 reg;
> -       u32 status_reg;
>         u8 *buffer = msg->buffer;
>         unsigned int i;
>         int ret;
> @@ -1011,12 +1010,14 @@ ssize_t analogix_dp_transfer(struct analogix_dp_device *dp,
>
>         /* Clear interrupt source for AUX CH access error */
>         reg = readl(dp->reg_base + ANALOGIX_DP_INT_STA);
> -       status_reg = readl(dp->reg_base + ANALOGIX_DP_AUX_CH_STA);
> -       if ((reg & AUX_ERR) || (status_reg & AUX_STATUS_MASK)) {
> +       if ((reg & AUX_ERR)) {
> +               u32 aux_status = readl(dp->reg_base + ANALOGIX_DP_AUX_CH_STA) &
> +                                AUX_STATUS_MASK;
> +
>                 writel(AUX_ERR, dp->reg_base + ANALOGIX_DP_INT_STA);
>
>                 dev_warn(dp->dev, "AUX CH error happened: %#x (%d)\n",
> -                        status_reg & AUX_STATUS_MASK, !!(reg & AUX_ERR));
> +                        aux_status, !!(reg & AUX_ERR));
>                 goto aux_error;
>         }
>
> --
> 2.39.2
>

Reviewed-by: Robert Foss <rfoss at kernel.org>