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Wed, 08 Jun 2022 06:04:17 -0700 Received: from mtkmbs11n1.mediatek.inc (172.21.101.185) by MTKMBS62DR.mediatek.inc (172.29.94.18) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Wed, 8 Jun 2022 05:54:15 -0700 Received: from mtkmbs11n1.mediatek.inc (172.21.101.185) by mtkmbs11n1.mediatek.inc (172.21.101.185) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.792.3; Wed, 8 Jun 2022 20:54:14 +0800 Received: from mtksdccf07 (172.21.84.99) by mtkmbs11n1.mediatek.inc (172.21.101.73) with Microsoft SMTP Server id 15.2.792.3 via Frontend Transport; Wed, 8 Jun 2022 20:54:14 +0800 Message-ID: <61ed067bc117a67ccdf64420401605c2fadfe43a.camel@mediatek.com> Subject: Re: [PATCH v10 18/21] drm/mediatek: Add mt8195 Embedded DisplayPort driver From: Rex-BC Chen To: CK Hu , Guillaume Ranquet , Chun-Kuang Hu , Philipp Zabel , David Airlie , Daniel Vetter , Rob Herring , Krzysztof Kozlowski , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , Matthias Brugger , Chunfeng Yun =?UTF-8?Q?=28=E4=BA=91=E6=98=A5=E5=B3=B0=29?= , Kishon Vijay Abraham I , Vinod Koul , "Helge Deller" , Jitao Shi =?UTF-8?Q?=28=E7=9F=B3=E8=AE=B0=E6=B6=9B=29?= CC: Markus Schneider-Pargmann , "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" Date: Wed, 8 Jun 2022 20:54:14 +0800 In-Reply-To: <79bea587e20de842d48dcb2e1da19e276f9d635b.camel@mediatek.com> References: <20220523104758.29531-1-granquet@baylibre.com> <20220523104758.29531-19-granquet@baylibre.com> <4329859ca11c13e7f6a9951b01a779fc391f029b.camel@mediatek.com> <79bea587e20de842d48dcb2e1da19e276f9d635b.camel@mediatek.com> X-Mailer: Evolution 3.28.5-0ubuntu0.18.04.2 MIME-Version: 1.0 X-MTK: N X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220608_060426_239055_8B3EFCEC X-CRM114-Status: GOOD ( 45.50 ) X-BeenThere: linux-phy@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: Linux Phy Mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-phy" Errors-To: linux-phy-bounces+linux-phy=archiver.kernel.org@lists.infradead.org On Wed, 2022-06-08 at 10:44 +0800, CK Hu wrote: > Hi, Rex: > > On Tue, 2022-06-07 at 20:44 +0800, Rex-BC Chen wrote: > > On Tue, 2022-06-07 at 14:44 +0800, CK Hu wrote: > > > Hi, Rex: > > > > > > On Mon, 2022-05-23 at 12:47 +0200, Guillaume Ranquet wrote: > > > > From: Markus Schneider-Pargmann > > > > > > > > This patch adds a 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 > > > > Jason-JH.Lin . > > > > > > > > Signed-off-by: Markus Schneider-Pargmann > > > > Signed-off-by: Guillaume Ranquet > > > > --- > > > > > > [snip] > > > > > > > + > > > > +static int mtk_dp_train_handler(struct mtk_dp *mtk_dp) > > > > +{ > > > > + bool training_done = false; > > > > + short max_retry = 50; > > > > + int ret = 0; > > > > + > > > > + do { > > > > + switch (mtk_dp->train_state) { > > > > + case MTK_DP_TRAIN_STATE_STARTUP: > > > > > > mtk_dp->train_state is initialized as MTK_DP_TRAIN_STATE_STARTUP > > > even > > > though HPD ISR does not exist. Does this mean HPD ISR is > > > redundant? > > > If > > > HPD ISR is not redundant, create a new state > > > MTK_DP_TRAIN_STATE_NONE > > > for init state. > > > > > > > Hello CK, > > > > I think we don't need MTK_DP_TRAIN_STATE_NONE. > > Because it's "DP_TRAIN_STATE" not "DP_STATE", I think it's ok if we > > start this state machine with "MTK_DP_TRAIN_STATE_STARTUP". > > The initial state is MTK_DP_TRAIN_STATE_STARTUP, and HPD thread would > change state from MTK_DP_TRAIN_STATE_STARTUP to > MTK_DP_TRAIN_STATE_STARTUP, this is redundant. So drop the state > change > in HPD thread. > ok, in edp it's redundant in mtk_dp_hpd_event_thread(), but I will add it back in dp patch. > > > > > > + mtk_dp_state_handler(mtk_dp); > > > > + mtk_dp->train_state = > > > > MTK_DP_TRAIN_STATE_CHECKCAP; > > > > + break; > > > > + > > > > + case MTK_DP_TRAIN_STATE_CHECKCAP: > > > > + if (mtk_dp_parse_capabilities(mtk_dp)) > > > > { > > > > + mtk_dp- > > > > >train_info.check_cap_count = 0; > > > > + mtk_dp->train_state = > > > > MTK_DP_TRAIN_STATE_CHECKEDID; > > > > + } else { > > > > + mtk_dp- > > > > >train_info.check_cap_count++; > > > > + > > > > + if (mtk_dp- > > > > >train_info.check_cap_count > > > > > > > > > > > > > + MTK_DP_CHECK_SINK_CAP_TIMEO > > > > UT_COUNT > > > > ) { > > > > + mtk_dp- > > > > > train_info.check_cap_count = 0; > > > > > > > > + mtk_dp->train_state = > > > > MTK_DP_TRAIN_STATE_DPIDLE; > > > > + ret = -ETIMEDOUT; > > > > + } > > > > + } > > > > + break; > > > > + > > > > + case MTK_DP_TRAIN_STATE_CHECKEDID: > > > > + mtk_dp->train_state = > > > > MTK_DP_TRAIN_STATE_TRAINING_PRE; > > > > > > MTK_DP_TRAIN_STATE_CHECKEDID is a redundant state, drop it. > > > > > > > + break; > > > > + > > > > + case MTK_DP_TRAIN_STATE_TRAINING_PRE: > > > > + mtk_dp_state_handler(mtk_dp); > > > > + mtk_dp->train_state = > > > > MTK_DP_TRAIN_STATE_TRAINING; > > > > + break; > > > > + > > > > + case MTK_DP_TRAIN_STATE_TRAINING: > > > > + ret = mtk_dp_train_start(mtk_dp); > > > > + if (ret == 0) { > > > > + mtk_dp_video_mute(mtk_dp, > > > > true); > > > > + mtk_dp->train_state = > > > > MTK_DP_TRAIN_STATE_NORMAL; > > > > + mtk_dp_fec_enable(mtk_dp, > > > > mtk_dp- > > > > > has_fec); > > > > > > > > + } else if (ret != -EAGAIN) { > > > > + mtk_dp->train_state = > > > > MTK_DP_TRAIN_STATE_DPIDLE; > > > > + } > > > > + break; > > > > + case MTK_DP_TRAIN_STATE_NORMAL: > > > > + mtk_dp_state_handler(mtk_dp); > > > > + training_done = true; > > > > + break; > > > > + case MTK_DP_TRAIN_STATE_DPIDLE: > > > > > > When would this case happen? > > > > > > Regards, > > > CK > > > > Yes, if it's disconnected if we are still training for dp. > > or failed to training min spec RBR. > > I mean, every time state change to MTK_DP_TRAIN_STATE_DPIDLE, it > would > jump out of this loop and would not get into this loop, so this case > would never get in. This is redundant, so remove this. > > Regards, > CK > ok, I will remove it BRs, Bo-Chen > > > > BRs, > > Rex > > > > > > > + break; > > > > + default: > > > > + break; > > > > + } > > > > + > > > > + if (ret) { > > > > + if (ret == -EAGAIN) > > > > + continue; > > > > + /* > > > > + * If we get any other error number, it > > > > doesn't > > > > + * make any sense to keep iterating. > > > > + */ > > > > + break; > > > > + } > > > > + } while (!training_done || --max_retry); > > > > + > > > > + return ret; > > > > +} > > > > > > > > > > > > -- linux-phy mailing list linux-phy@lists.infradead.org https://lists.infradead.org/mailman/listinfo/linux-phy