Hi Philipp,

On Tue, Sep 07, 2021 at 10:47:41AM +0200, Philipp Zabel wrote:

Hi Markus,

On Mon, 2021-09-06 at 21:35 +0200, Markus Schneider-Pargmann wrote:

quoted

This patch adds a DisplayPort driver for the Mediatek mt8195 SoC.

It supports both functional units on the mt8195, the embedded
DisplayPort as well as the external DisplayPort units. It offers
hot-plug-detection, audio up to 8 channels, and DisplayPort 1.4 with up
to 4 lanes.

This driver is based on an initial version by
Jason-JH.Lin [off-list ref].

Signed-off-by: Markus Schneider-Pargmann <msp@baylibre.com>
---

[...]

quoted

diff --git a/drivers/gpu/drm/mediatek/mtk_dp.c b/drivers/gpu/drm/mediatek/mtk_dp.c
new file mode 100644
index 000000000000..1bd07c8d2f69
--- /dev/null
+++ b/drivers/gpu/drm/mediatek/mtk_dp.c

@@ -0,0 +1,2881 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2019 MediaTek Inc.
+ * Copyright (c) 2021 BayLibre
+ */
+

[...]

quoted

+#include <linux/component.h>

[...]

quoted

+#include <linux/extcon.h>
+#include <linux/extcon-provider.h>

[...]

quoted

+#include <linux/kthread.h>
+#include <linux/mfd/syscon.h>

[...]

quoted

+#include <linux/of_gpio.h>
+#include <linux/of_graph.h>

[...]

quoted

+#include <linux/phy/phy.h>

The list of included headers could be pruned a bit, from a quick look it
seems like neither of these are actually used.

Thank you. I fixed the includes for the next version.

[...]

quoted

+static void mtk_dp_ssc_enable(struct mtk_dp *mtk_dp, bool enable)
+{
+	mtk_dp_update_bits(mtk_dp, MTK_DP_TOP_PWR_STATE, DP_PWR_STATE_BANDGAP,
+			   DP_PWR_STATE_MASK);
+	mtk_dp_update_bits(mtk_dp, DP_PHY_DIG_PLL_CTL_1,
+			   enable ? TPLL_SSC_EN : 0, TPLL_SSC_EN);
+	mtk_dp_update_bits(mtk_dp, MTK_DP_TOP_PWR_STATE,
+			   DP_PWR_STATE_BANDGAP_TPLL_LANE, DP_PWR_STATE_MASK);
+
+	udelay(50);

Can usleep_range() be used here? Same for the other delays.

Yes, thanks, I replaced it here and everywhere else.

[...]

quoted

+static void mtk_dp_hpd_sink_event(struct mtk_dp *mtk_dp)
+{

[...]

quoted

+
+	if (DP_GET_SINK_COUNT(sink_count) &&
+	    (link_status[2] & DP_DOWNSTREAM_PORT_STATUS_CHANGED)) {
+		mtk_dp->train_info.check_cap_count = 0;
+		kfree(mtk_dp->edid);
+		mtk_dp->edid = NULL;

Should this be protect by a lock? This looks like it could race with the
access in mtk_dp_edid_parse_audio_capabilities() or mtk_dp_get_edid()

Completely right, I guarded all edid accesses with a mutex now. Thanks.

[...]

quoted

+static int mtk_dp_train_handler(struct mtk_dp *mtk_dp)
+{
+	int ret = 0;
+
+	ret = mtk_dp_train_hpd_handle(mtk_dp);
+
+	if (!mtk_dp->train_info.cable_plugged_in)
+		return -ENODEV;
+
+	if (mtk_dp->train_state == MTK_DP_TRAIN_STATE_NORMAL)
+		return ret;
+
+	switch (mtk_dp->train_state) {

[...]

quoted

+	case MTK_DP_TRAIN_STATE_TRAINING:
+		ret = mtk_dp_train_start(mtk_dp);
+		if (!ret) {
+			mtk_dp_video_mute(mtk_dp, true);
+			mtk_dp_audio_mute(mtk_dp, true);
+			mtk_dp->train_state = MTK_DP_TRAIN_STATE_CHECKTIMING;
+			mtk_dp_fec_enable(mtk_dp, mtk_dp->has_fec);
+		}  else if (ret != -EAGAIN)
+			mtk_dp->train_state = MTK_DP_TRAIN_STATE_DPIDLE;

A small whitespace issue and missing braces.

Thanks for spotting, fixed.

Consider running this through checkpatch.pl --strict once for style
issues.

Thanks for the tip, I didn't know about --strict. I now added it to my
editor tooling. Interesting thing: It picked up the missing braces as
well as all the udelays, but not the extra space before else.

[...]

quoted

+static irqreturn_t mtk_dp_hpd_event(int hpd, void *dev)
+{
+	struct mtk_dp *mtk_dp = dev;
+	uint32_t irq_status;
+
+	irq_status = mtk_dp_read(mtk_dp, MTK_DP_TOP_IRQ_STATUS);
+
+	if (!irq_status)
+		return IRQ_HANDLED;

This check seems superfluous given that only the
RGS_IRQ_STATUS_TRANSMITTER bit is checked right below:

Thanks, I removed it.

quoted

+	if (irq_status & RGS_IRQ_STATUS_TRANSMITTER)
+		return mtk_dp_hpd_isr_handler(mtk_dp);
+
+	return IRQ_HANDLED;
+}

[...]

quoted

+static struct edid *mtk_dp_get_edid(struct drm_bridge *bridge,
+				    struct drm_connector *connector)
+{
+	struct mtk_dp *mtk_dp = mtk_dp_from_bridge(bridge);
+	bool pre_enabled = mtk_dp->pre_enabled;
+
+	if (mtk_dp->edid)
+		kfree(mtk_dp->edid);

Unnecessary check, kfree() accepts NULL.

Fixed.

Thank you Philipp for the review.

Best,
Markus

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