On Tue, 2022-07-26 at 14:42 +0800, Rex-BC Chen wrote:

On Mon, 2022-07-25 at 17:16 +0800, CK Hu wrote:

quoted

Hi, Bo-Chen:

On Tue, 2022-07-12 at 19:12 +0800, Bo-Chen Chen wrote:

quoted

From: Markus Schneider-Pargmann <msp@baylibre.com>

This patch adds a embedded displayport driver for the MediaTek
mt8195
SoC.

It supports the MT8195, the embedded DisplayPort units. It offers
DisplayPort 1.4 with up to 4 lanes.

The driver creates a child device for the phy. The child device
will
never exist without the parent being active. As they are sharing
a
register range, the parent passes a regmap pointer to the child
so
that
both can work with the same register range. The phy driver sets
device
data that is read by the parent to get the phy device that can be
used
to control the phy properties.

This driver is based on an initial version by
Jitao shi [off-list ref]

Signed-off-by: Markus Schneider-Pargmann <msp@baylibre.com>
Signed-off-by: Guillaume Ranquet <redacted>
Signed-off-by: Bo-Chen Chen <redacted>
---

[snip]

quoted

+
+static int mtk_dp_training(struct mtk_dp *mtk_dp)
+{
+	short max_retry = 50;
+	int ret;
+
+	do {
+		ret = mtk_dp_train_start(mtk_dp);
+		if (!ret)
+			break;
+		else if (ret != -EAGAIN)
+			return ret;
+	} while (--max_retry);

mtk_dp_train_start() would never return -EAGAIN, so drop this while
loop.

Regards,
CK

Hello CK,

the function will not return -EAGAIN, but we still want to retry 50
times if mtk_dp_train_start() is failed. If we retry 50 times and it
is
still failed. We can confirm there are some issues for the device.

I will remove the else if of -EAGAIN and keep th while loop.

In this version, it never retry. And I believe you've tested this no-
retry version. If this no-retry version works fine, why do you insist
on retry? If you really need retry, merge this retry into
mtk_dp_train_start() because mtk_dp_train_start() have already retry.

Regards,
CK

BRs,
Bo-Chen

quoted

quoted

+	if (!max_retry)
+		return -ETIMEDOUT;
+
+	ret = mtk_dp_video_config(mtk_dp);
+	if (ret)
+		return ret;
+	mtk_dp_video_enable(mtk_dp, true);
+
+	return 0;
+}
+