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[2a02:8440:6240:cc41:3074:96af:9642:3]) by smtp.gmail.com with ESMTPSA id p16-20020a5d6390000000b00203ffebddf3sm7547464wru.99.2022.03.25.10.17.26 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 25 Mar 2022 10:17:27 -0700 (PDT) From: Guillaume Ranquet To: chunkuang.hu@kernel.org, p.zabel@pengutronix.de, airlied@linux.ie, daniel@ffwll.ch, robh+dt@kernel.org, maarten.lankhorst@linux.intel.com, mripard@kernel.org, tzimmermann@suse.de, matthias.bgg@gmail.com, chunfeng.yun@mediatek.com, kishon@ti.com, vkoul@kernel.org, deller@gmx.de, ck.hu@mediatek.com, jitao.shi@mediatek.com, angelogioacchino.delregno@collabora.com Cc: dri-devel@lists.freedesktop.org, linux-mediatek@lists.infradead.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-phy@lists.infradead.org, linux-fbdev@vger.kernel.org, markyacoub@google.com, Rex-BC Chen Subject: [PATCH 20/22] drm/mediatek: add hpd debounce Date: Fri, 25 Mar 2022 18:15:09 +0100 Message-Id: <20220325171511.23493-21-granquet@baylibre.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20220325171511.23493-1-granquet@baylibre.com> References: <20220325171511.23493-1-granquet@baylibre.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Jitao Shi From the DP spec 1.4a chapter 3.3, upstream devices should implement HPD signal de-bouncing on an external connection. A period of 100ms should be used to detect an HPD connect event. To cover these cases, HPD de-bounce should be implemented only after HPD low has been detected for at least 100ms. Therefore, 1. If HPD is low (which means plugging out) for longer than 100ms: we need to do de-bouncing (which means we need to wait for 100ms). 2. If HPD low is for less than 100ms: we don't need to care about the de-bouncing. In this patch, we start a 100ms timer and use a need_debounce boolean to implement the feature. Two cases when HPD is high: 1. If the timer is expired (>100ms): - need_debounce is true. - When HPD high (plugging event comes), need_debounce will be true and then we need to do de-bouncing (wait for 100ms). 2. If the timer is not expired (<100ms): - need_debounce is false. - When HPD high (plugging event comes), need_debounce will be false and no need to do de-bouncing. HPD_______ __________________ | |<- 100ms -> |____________| <- 100ms -> Without HPD de-bouncing, USB-C to HDMI Adapaters will not be detected. The change has been successfully tested with the following devices: - Dell Adapter - USB-C to HDMI - Acer 1in1 HDMI dongle - Ugreen 1in1 HDMI dongle - innowatt HDMI + USB3 hub - Acer 2in1 HDMI dongle - Apple 3in1 HDMI dongle (A2119) - J5Create 3in1 HDMI dongle (JAC379) Tested-by: Rex-BC Chen Reviewed-by: Rex-BC Chen Signed-off-by: Jitao Shi Signed-off-by: Guillaume Ranquet --- drivers/gpu/drm/mediatek/mtk_dp.c | 46 +++++++++++++++++++++++++++++++ 1 file changed, 46 insertions(+) diff --git a/drivers/gpu/drm/mediatek/mtk_dp.c b/drivers/gpu/drm/mediatek/m= tk_dp.c index d9606c743a9e..4981a3a3b9ca 100644 --- a/drivers/gpu/drm/mediatek/mtk_dp.c +++ b/drivers/gpu/drm/mediatek/mtk_dp.c @@ -174,6 +174,33 @@ struct mtk_dp { struct device *codec_dev; u8 connector_eld[MAX_ELD_BYTES]; struct drm_connector *conn; + bool need_debounce; + struct timer_list debounce_timer; +}; + +enum mtk_dp_sdp_type { + MTK_DP_SDP_NONE =3D 0x00, + MTK_DP_SDP_ACM =3D 0x01, + MTK_DP_SDP_ISRC =3D 0x02, + MTK_DP_SDP_AVI =3D 0x03, + MTK_DP_SDP_AUI =3D 0x04, + MTK_DP_SDP_SPD =3D 0x05, + MTK_DP_SDP_MPEG =3D 0x06, + MTK_DP_SDP_NTSC =3D 0x07, + MTK_DP_SDP_VSP =3D 0x08, + MTK_DP_SDP_VSC =3D 0x09, + MTK_DP_SDP_EXT =3D 0x0A, + MTK_DP_SDP_PPS0 =3D 0x0B, + MTK_DP_SDP_PPS1 =3D 0x0C, + MTK_DP_SDP_PPS2 =3D 0x0D, + MTK_DP_SDP_PPS3 =3D 0x0E, + MTK_DP_SDP_DRM =3D 0x10, + MTK_DP_SDP_MAX_NUM +}; + +struct mtk_dp_sdp_packet { + enum mtk_dp_sdp_type type; + struct dp_sdp sdp; }; =20 static bool mtk_dp_is_edp(struct mtk_dp *mtk_dp) @@ -1814,6 +1841,9 @@ static irqreturn_t mtk_dp_hpd_event_thread(int hpd, v= oid *dev) if (event < 0) return IRQ_HANDLED; =20 + if (mtk_dp->need_debounce && mtk_dp->train_info.cable_plugged_in) + msleep(100); + if (mtk_dp->drm_dev) { dev_info(mtk_dp->dev, "drm_helper_hpd_irq_event\n"); drm_helper_hpd_irq_event(mtk_dp->bridge.dev); @@ -1892,6 +1922,11 @@ static irqreturn_t mtk_dp_hpd_isr_handler(struct mtk= _dp *mtk_dp) } train_info->cable_state_change =3D true; =20 + if (!train_info->cable_plugged_in) { + mod_timer(&mtk_dp->debounce_timer, jiffies + msecs_to_jiffies(100) - 1); + mtk_dp->need_debounce =3D false; + } + return IRQ_WAKE_THREAD; } =20 @@ -2339,6 +2374,13 @@ static const struct drm_bridge_funcs mtk_dp_bridge_f= uncs =3D { .detect =3D mtk_dp_bdg_detect, }; =20 +static void mtk_dp_debounce_timer(struct timer_list *t) +{ + struct mtk_dp *mtk_dp =3D from_timer(mtk_dp, t, debounce_timer); + + mtk_dp->need_debounce =3D true; +} + static int mtk_dp_probe(struct platform_device *pdev) { struct mtk_dp *mtk_dp; @@ -2396,6 +2438,9 @@ static int mtk_dp_probe(struct platform_device *pdev) mtk_dp->bridge.of_node =3D dev->of_node; mtk_dp->bridge.type =3D DRM_MODE_CONNECTOR_eDP; =20 + mtk_dp->need_debounce =3D true; + timer_setup(&mtk_dp->debounce_timer, mtk_dp_debounce_timer, 0); + mtk_dp->bridge.ops =3D DRM_BRIDGE_OP_DETECT | DRM_BRIDGE_OP_EDID | DRM_BRIDGE_OP_HPD; drm_bridge_add(&mtk_dp->bridge); @@ -2415,6 +2460,7 @@ static int mtk_dp_remove(struct platform_device *pdev) struct mtk_dp *mtk_dp =3D platform_get_drvdata(pdev); =20 mtk_dp_video_mute(mtk_dp, true); + del_timer_sync(&mtk_dp->debounce_timer); =20 pm_runtime_disable(&pdev->dev); =20 --=20 2.34.1