[PATCH v12 16/18] drm: bridge: analogix/dp: expand the wait time for looking AUX CH reply flag

Yakir Yang ykk at rock-chips.com
Wed Dec 23 04:51:04 PST 2015

On Rockchip platform, sometimes driver would failed at reading EDID
message, and it's caused by the AUX reply flag wouldn't received under
the 100*10us wait time.

But after expand the wait time a little, the AUX reply flag would be
set, so maybe the wait time is a little critical. Besides the analogix
dp book haven't reminded the standard wait for looking AUX reply flag,
so I thought it's okay to expand the wait time.

And the external wait time won't hurt Exynos DP too much, cause they
wouldn't meet this problem, then driver would received the reply command
very soon, so no more additional wait time would bring to Exynos platform.

Signed-off-by: Yakir Yang <ykk at rock-chips.com>
Changes in v12:
- Using another way to expand the AUX reply wait time (Jingoo)

Changes in v11: None
Changes in v10: None
Changes in v9: None
Changes in v8: None
Changes in v7: None
Changes in v6: None
Changes in v5: None
Changes in v4: None
Changes in v3: None
Changes in v2: None

 drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c b/drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c
index cba3ffd..8687eea 100644
--- a/drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c
+++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c
@@ -471,7 +471,7 @@ int analogix_dp_start_aux_transaction(struct analogix_dp_device *dp)
 	int reg;
 	int retval = 0;
-	int timeout_loop = 0;
+	unsigned long timeout;
 	/* Enable AUX CH operation */
 	reg = readl(dp->reg_base + ANALOGIX_DP_AUX_CH_CTL_2);
@@ -479,14 +479,12 @@ int analogix_dp_start_aux_transaction(struct analogix_dp_device *dp)
 	writel(reg, dp->reg_base + ANALOGIX_DP_AUX_CH_CTL_2);
 	/* Is AUX CH command reply received? */
-	reg = readl(dp->reg_base + ANALOGIX_DP_INT_STA);
-	while (!(reg & RPLY_RECEIV)) {
-		timeout_loop++;
-		if (DP_TIMEOUT_LOOP_COUNT < timeout_loop) {
+	timeout = jiffies + msecs_to_jiffies(5);
+	while ((readl(dp->reg_base + ANALOGIX_DP_INT_STA) & RPLY_RECEIV) == 0) {
+		if (time_after(jiffies, timeout)) {
 			dev_err(dp->dev, "AUX CH command reply failed!\n");
 			return -ETIMEDOUT;
-		reg = readl(dp->reg_base + ANALOGIX_DP_INT_STA);
 		usleep_range(10, 11);

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