[PATCH v2 13/14] drm/bridge: analogix_dp: only read AUX status when an error occured

[Lucas Stach]

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 occurred and we can expect a different
status than OK.

Signed-off-by: Lucas Stach <l.st...@pengutronix.de>
Reviewed-by: Robert Foss <rf...@kernel.org>
Tested-by: Heiko Stuebner <he...@sntech.de> (rk3288-veyron and rk3399-gru)
---
 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