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Message-ID: <d0aa557c16b9fab64253a2a52c2eb66a76029b4b.camel@mediatek.com>
Date: Tue, 5 Aug 2025 03:52:32 +0000
From: CK Hu (胡俊光) <ck.hu@...iatek.com>
To: "towwy321@...il.com" <towwy321@...il.com>, "chunkuang.hu@...nel.org"
<chunkuang.hu@...nel.org>, "simona@...ll.ch" <simona@...ll.ch>,
AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>,
"airlied@...il.com" <airlied@...il.com>, "msp@...libre.com"
<msp@...libre.com>, "p.zabel@...gutronix.de" <p.zabel@...gutronix.de>,
"matthias.bgg@...il.com" <matthias.bgg@...il.com>, "granquet@...libre.com"
<granquet@...libre.com>
CC: Rex-BC Chen (陳柏辰) <Rex-BC.Chen@...iatek.com>,
"dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
"linux-mediatek@...ts.infradead.org" <linux-mediatek@...ts.infradead.org>,
"linux-arm-kernel@...ts.infradead.org"
<linux-arm-kernel@...ts.infradead.org>, "linux-kernel@...r.kernel.org"
<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] drm/mediatek: dp: Fix suspend/resume training failure
On Tue, 2025-08-05 at 00:03 +0800, Haru Zheng wrote:
> External email : Please do not click links or open attachments until you have verified the sender or the content.
>
>
> When suspending and resuming DisplayPort via Type-C,
> link training will be fail.
>
> This patch backports the software IRQ handling for DP,
> as eDP uses hardware IRQ while DP uses software IRQ.
> Additionally, cable_plugged_in is flipped in
> mtk_dp_hpd_event to ensure correct hotplug detection
> during resume.
>
> These changes fix the DP training failure after suspend/resume.
>
> Fixes: f70ac097a2cf ("drm/mediatek: Add MT8195 Embedded DisplayPort driver")
> Signed-off-by: Haru Zheng <towwy321@...il.com>
>
> ---
>
> Changes since v1:
> - Fixed indentation to use tabs
> - Simplified swirq_enable() logic with ternary
> - Removed unnecessary memset()
> - Replaced dev_info() with dev_dbg()
> - Add mtk_dp_bridge_hpd_notify() declaration to struct drm_bridge_funcs mtk_dp_bridge_funcs
> - Removed IRQ enable from probe() to avoid enabling IRQ for eDP
> - Corrected HW/SW IRQ logic:
> * eDP uses hardware IRQ, DP uses software IRQ
> * Previously some logic was reversed causing issues
> - Fixed hotplug detection logic in mtk_dp_hpd_event:
> * cable_plugged_in flag inverted to ensure correct detection on resume
>
> Code flow:
> - On suspend, DP disables training and IRQs accordingly.
> - On resume, IRQs for DP are re-enabled via software IRQ handler.
> - HPD events are processed with correct plug/unplug state, ensuring training succeeds.
>
> ---
> drivers/gpu/drm/mediatek/mtk_dp.c | 94 ++++++++++++++++++++++++---
> drivers/gpu/drm/mediatek/mtk_dp_reg.h | 3 +
> 2 files changed, 87 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/gpu/drm/mediatek/mtk_dp.c b/drivers/gpu/drm/mediatek/mtk_dp.c
> index bef6eeb30d3e..b0f96c7c279e 100644
> --- a/drivers/gpu/drm/mediatek/mtk_dp.c
> +++ b/drivers/gpu/drm/mediatek/mtk_dp.c
> @@ -1012,6 +1012,12 @@ static u32 mtk_dp_swirq_get_clear(struct mtk_dp *mtk_dp)
> return irq_status;
> }
>
> +static void mtk_dp_swirq_enable(struct mtk_dp *mtk_dp, bool enable)
> +{
> + mtk_dp_update_bits(mtk_dp, MTK_DP_TRANS_P0_35C4, enable ? 0 : 0xFFFF,
> + SW_IRQ_FINAL_STATUS_DP_TRANS_P0_MASK);
> +}
> +
> static u32 mtk_dp_hwirq_get_clear(struct mtk_dp *mtk_dp)
> {
> u32 irq_status = (mtk_dp_read(mtk_dp, MTK_DP_TRANS_P0_3418) &
> @@ -2031,8 +2037,8 @@ static irqreturn_t mtk_dp_hpd_event(int hpd, void *dev)
> spin_unlock_irqrestore(&mtk_dp->irq_thread_lock, flags);
>
> if (cable_sta_chg) {
> - if (!!(mtk_dp_read(mtk_dp, MTK_DP_TRANS_P0_3414) &
> - HPD_DB_DP_TRANS_P0_MASK))
> + if (!(mtk_dp_read(mtk_dp, MTK_DP_TRANS_P0_3414) &
> + HPD_DB_DP_TRANS_P0_MASK))
Why do you change this.
Original code works normally.
This change may cause problem.
> mtk_dp->train_info.cable_plugged_in = true;
> else
> mtk_dp->train_info.cable_plugged_in = false;
> @@ -2252,7 +2258,7 @@ static ssize_t mtk_dp_aux_transfer(struct drm_dp_aux *mtk_aux,
> to_access, &msg->reply);
>
> if (ret) {
> - dev_info(mtk_dp->dev,
> + dev_dbg(mtk_dp->dev,
> "Failed to do AUX transfer: %d\n", ret);
This is error case. Do not use dev_dbg().
> goto err;
> }
> @@ -2265,6 +2271,35 @@ static ssize_t mtk_dp_aux_transfer(struct drm_dp_aux *mtk_aux,
> return ret;
> }
>
> +static void mtk_dp_swirq_hpd(struct mtk_dp *mtk_dp, u8 conn)
> +{
> + u32 data;
> +
> + data = mtk_dp_read(mtk_dp, MTK_DP_TRANS_P0_3414);
data is useless. Drop it.
> +
> + mtk_dp_update_bits(mtk_dp, MTK_DP_TRANS_P0_3414,
> + HPD_OVR_EN_DP_TRANS_P0_MASK,
> + HPD_OVR_EN_DP_TRANS_P0_MASK);
Where do you define HPD_OVR_EN_DP_TRANS_P0_MASK?
> +
> + if (conn)
> + mtk_dp_update_bits(mtk_dp, MTK_DP_TRANS_P0_3414,
> + HPD_SET_DP_TRANS_P0_MASK,
> + HPD_SET_DP_TRANS_P0_MASK);
Where do you define HPD_SET_DP_TRANS_P0_MASK?
> + else
> + mtk_dp_update_bits(mtk_dp, MTK_DP_TRANS_P0_3414,
> + 0,
> + HPD_SET_DP_TRANS_P0_MASK);
> +}
> +
> +static void mtk_dp_swirq_hpd_interrupt_set(struct mtk_dp *mtk_dp, u8 status)
> +{
> + dev_dbg(mtk_dp->dev, "[DPTX] status:%d [2:DISCONNECT, 4:CONNECT]\n", status);
> +
> + mtk_dp_swirq_hpd(mtk_dp, status == MTK_DP_HPD_CONNECT ? TRUE : FALSE);
> + mtk_dp_update_bits(mtk_dp, MTK_DP_TRANS_P0_35C0, status,
> + SW_IRQ_SET_DP_TRANS_P0_MASK);
> +}
> +
> static int mtk_dp_poweron(struct mtk_dp *mtk_dp)
> {
> int ret;
> @@ -2326,7 +2361,13 @@ static int mtk_dp_bridge_attach(struct drm_bridge *bridge,
> if (mtk_dp->bridge.type != DRM_MODE_CONNECTOR_eDP) {
> irq_clear_status_flags(mtk_dp->irq, IRQ_NOAUTOEN);
> enable_irq(mtk_dp->irq);
> + /* eDP does use HW IRQs */
'mtk_dp->bridge.type != DRM_MODE_CONNECTOR_eDP' means here is DP.
The comment is wrong.
> mtk_dp_hwirq_enable(mtk_dp, true);
> + mtk_dp_swirq_enable(mtk_dp, false);
> + } else {
> + /* DP does use SW IRQs */
Here is eDP.
eDP does not need IRQ.
If you want to use IRQ, add comment to describe why you need.
> + mtk_dp_hwirq_enable(mtk_dp, false);
> + mtk_dp_swirq_enable(mtk_dp, true);
> }
>
> return 0;
> @@ -2534,7 +2575,7 @@ static int mtk_dp_bridge_atomic_check(struct drm_bridge *bridge,
>
> dev_dbg(mtk_dp->dev, "input format 0x%04x, output format 0x%04x\n",
> bridge_state->input_bus_cfg.format,
> - bridge_state->output_bus_cfg.format);
> + bridge_state->output_bus_cfg.format);
This is a cleanup modification.
This is not related to the title.
If you want to modify this, collect all cleanup in this file and separate to another patch.
>
> if (input_bus_format == MEDIA_BUS_FMT_YUYV8_1X16)
> mtk_dp->info.format = DP_PIXELFORMAT_YUV422;
> @@ -2552,6 +2593,30 @@ static int mtk_dp_bridge_atomic_check(struct drm_bridge *bridge,
> return 0;
> }
>
> +static void mtk_dp_bridge_hpd_notify(struct drm_bridge *bridge,
> + enum drm_connector_status status)
Why add this.
Original code could work normally.
If this is not related to the title, separate this to another patch.
> +{
> + struct mtk_dp *mtk_dp = mtk_dp_from_bridge(bridge);
> + struct mtk_dp_train_info *train_info = &mtk_dp->train_info;
> +
> + if (mtk_dp->bridge.type != DRM_MODE_CONNECTOR_eDP) {
> + if (mtk_dp->hpd_state != status) {
> + if (status == connector_status_disconnected) {
> + train_info->cable_plugged_in = false;
> + } else {
> + mtk_dp_update_bits(mtk_dp, MTK_DP_TRANS_P0_3414,
> + HPD_OVR_EN_DP_TRANS_P0_MASK,
> + HPD_OVR_EN_DP_TRANS_P0_MASK);
> + mtk_dp_update_bits(mtk_dp, MTK_DP_TRANS_P0_3414,
> + HPD_SET_DP_TRANS_P0_MASK,
> + HPD_SET_DP_TRANS_P0_MASK);
> + train_info->cable_plugged_in = true;
> + }
> + mtk_dp->hpd_state = status;
> + }
> + }
> +}
> +
> static const struct drm_bridge_funcs mtk_dp_bridge_funcs = {
> .atomic_check = mtk_dp_bridge_atomic_check,
> .atomic_duplicate_state = drm_atomic_helper_bridge_duplicate_state,
> @@ -2566,6 +2631,7 @@ static const struct drm_bridge_funcs mtk_dp_bridge_funcs = {
> .mode_valid = mtk_dp_bridge_mode_valid,
> .edid_read = mtk_dp_edid_read,
> .detect = mtk_dp_bdg_detect,
> + .hpd_notify = mtk_dp_bridge_hpd_notify,
> };
>
> static void mtk_dp_debounce_timer(struct timer_list *t)
> @@ -2800,9 +2866,6 @@ static int mtk_dp_probe(struct platform_device *pdev)
> mtk_dp_initialize_aux_settings(mtk_dp);
> mtk_dp_power_enable(mtk_dp);
>
> - /* Disable HW interrupts: we don't need any for eDP */
> - mtk_dp_hwirq_enable(mtk_dp, false);
> -
> /*
> * Power on the AUX to allow reading the EDID from aux-bus:
> * please note that it is necessary to call power off in the
> @@ -2861,10 +2924,15 @@ static int mtk_dp_suspend(struct device *dev)
> struct mtk_dp *mtk_dp = dev_get_drvdata(dev);
>
> mtk_dp_power_disable(mtk_dp);
> - if (mtk_dp->bridge.type != DRM_MODE_CONNECTOR_eDP)
> +
> + if (mtk_dp->bridge.type == DRM_MODE_CONNECTOR_eDP) {
eDP does not need IRQ.
If you want to use IRQ, add comment to describe why you need.
> mtk_dp_hwirq_enable(mtk_dp, false);
> - pm_runtime_put_sync(dev);
> + } else {
> + mtk_dp_swirq_hpd_interrupt_set(mtk_dp, MTK_DP_HPD_DISCONNECT);
> + mtk_dp_swirq_enable(mtk_dp, false);
> + }
>
> + pm_runtime_put_sync(dev);
> return 0;
> }
>
> @@ -2874,8 +2942,14 @@ static int mtk_dp_resume(struct device *dev)
>
> pm_runtime_get_sync(dev);
> mtk_dp_init_port(mtk_dp);
> - if (mtk_dp->bridge.type != DRM_MODE_CONNECTOR_eDP)
> +
> + if (mtk_dp->bridge.type == DRM_MODE_CONNECTOR_eDP) {
> mtk_dp_hwirq_enable(mtk_dp, true);
eDP does not need IRQ.
If you want to use IRQ, add comment to describe why you need.
Regards,
CK
> + } else {
> + mtk_dp_swirq_hpd_interrupt_set(mtk_dp, MTK_DP_HPD_CONNECT);
> + mtk_dp_swirq_enable(mtk_dp, true);
> + }
> +
> mtk_dp_power_enable(mtk_dp);
>
> return 0;
> diff --git a/drivers/gpu/drm/mediatek/mtk_dp_reg.h b/drivers/gpu/drm/mediatek/mtk_dp_reg.h
> index 8ad7a9cc259e..7c97e230be50 100644
> --- a/drivers/gpu/drm/mediatek/mtk_dp_reg.h
> +++ b/drivers/gpu/drm/mediatek/mtk_dp_reg.h
> @@ -286,7 +286,10 @@
> #define POST_MISC_DATA_LANE1_OV_DP_TRANS_P0_MASK BIT(9)
> #define POST_MISC_DATA_LANE2_OV_DP_TRANS_P0_MASK BIT(10)
> #define POST_MISC_DATA_LANE3_OV_DP_TRANS_P0_MASK BIT(11)
> +#define MTK_DP_TRANS_P0_35C0 0x35c0
> +#define MTK_DP_TRANS_P0_35C4 0x35c4
> #define MTK_DP_TRANS_P0_35C8 0x35c8
> +#define SW_IRQ_SET_DP_TRANS_P0_MASK GENMASK(15, 0)
> #define SW_IRQ_CLR_DP_TRANS_P0_MASK GENMASK(15, 0)
> #define SW_IRQ_STATUS_DP_TRANS_P0_MASK GENMASK(15, 0)
> #define MTK_DP_TRANS_P0_35D0 0x35d0
> --
> 2.23.0
>
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