Re: [PATCH v11 05/10] drm/mediatek: Add MT8195 Embedded DisplayPort driver

Hi, Bo-Chen:

On Fri, 2022-06-10 at 18:55 +0800, Bo-Chen Chen wrote:

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>
[Bo-Chen: Cleanup the drivers and modify comments from reviewers]
Signed-off-by: Bo-Chen Chen <redacted>
---

[snip]

+
+static int mtk_dp_train_set_pattern(struct mtk_dp *mtk_dp, int
pattern)
+{
+	if (pattern < 0 || pattern > 4) {

The caller would pass pattern from 0 to 4, so this checking is
redundant. Remove it and this function would always return true, so let
this function be void.

Regards,
CK

+		drm_err(mtk_dp->drm_dev,
+			"Implementation error, no such pattern %d\n",
pattern);
+		return -EINVAL;
+	}
+
+	/* TPS1 */
+	if (pattern == 1)
+		mtk_dp_set_idle_pattern(mtk_dp, false);
+
+	mtk_dp_update_bits(mtk_dp,
+			   MTK_DP_TRANS_P0_3400,
+			   pattern ?
+			   BIT(pattern - 1) <<
PATTERN1_EN_DP_TRANS_P0_SHIFT :
+			   0,
+			   PATTERN1_EN_DP_TRANS_P0_MASK |
+			   PATTERN2_EN_DP_TRANS_P0_MASK |
+			   PATTERN3_EN_DP_TRANS_P0_MASK |
+			   PATTERN4_EN_DP_TRANS_P0_MASK);
+	return 0;
+}

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