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Tue, 06 Sep 2022 05:10:15 -0700 (PDT) MIME-Version: 1.0 References: <20220903130833.541463-1-xji@analogixsemi.com> <20220906025753.GA642918@anxtwsw-Precision-3640-Tower> In-Reply-To: <20220906025753.GA642918@anxtwsw-Precision-3640-Tower> From: Robert Foss Date: Tue, 6 Sep 2022 14:10:05 +0200 Message-ID: Subject: Re: [PATCH] drm/bridge: anx7625: Set HPD irq detect window to 2ms To: Xin Ji Content-Type: text/plain; charset="UTF-8" X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: dri-devel@lists.freedesktop.org, Jonas Karlman , David Airlie , qwen@analogixsemi.com, Neil Armstrong , linux-kernel@vger.kernel.org, Jernej Skrabec , mliu@analogixsemi.com, Laurent Pinchart , Andrzej Hajda , hsinyi@chromium.org, bliang@analogixsemi.com Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" On Tue, 6 Sept 2022 at 04:58, Xin Ji wrote: > > On Mon, Sep 05, 2022 at 06:48:06PM +0200, Robert Foss wrote: > > Hi Xin, > > > > On Sat, 3 Sept 2022 at 15:09, Xin Ji wrote: > > > > > > Some panels trigger HPD irq due to noise, the HPD debounce > > > may be 1.8ms, exceeding the default irq detect window, ~1.4ms. > > > This patch set HPD irq detection window to 2ms to > > > tolerate the HPD noise. > > > > > > Signed-off-by: Xin Ji > > > --- > > > drivers/gpu/drm/bridge/analogix/anx7625.c | 14 ++++++++++++++ > > > drivers/gpu/drm/bridge/analogix/anx7625.h | 6 ++++++ > > > 2 files changed, 20 insertions(+) > > > > > > diff --git a/drivers/gpu/drm/bridge/analogix/anx7625.c b/drivers/gpu/drm/bridge/analogix/anx7625.c > > > index c74b5df4cade..0c323b5a1c99 100644 > > > --- a/drivers/gpu/drm/bridge/analogix/anx7625.c > > > +++ b/drivers/gpu/drm/bridge/analogix/anx7625.c > > > @@ -1440,6 +1440,20 @@ static void anx7625_start_dp_work(struct anx7625_data *ctx) > > > > > > static int anx7625_read_hpd_status_p0(struct anx7625_data *ctx) > > > { > > > + int ret; > > > + > > > + /* Set irq detect window to 2ms */ > > > + ret = anx7625_reg_write(ctx, ctx->i2c.tx_p2_client, > > > + HPD_DET_TIMER_BIT0_7, HPD_TIME & 0xFF); > > > + ret |= anx7625_reg_write(ctx, ctx->i2c.tx_p2_client, > > > + HPD_DET_TIMER_BIT8_15, > > > + (HPD_TIME >> 8) & 0xFF); > > > + ret |= anx7625_reg_write(ctx, ctx->i2c.tx_p2_client, > > > + HPD_DET_TIMER_BIT16_23, > > > + (HPD_TIME >> 16) & 0xFF); > > > > Does the HPD debounce timer register need to be written for every HPD > > status read? > Hi Robert Foss, yes, it is better to set it in every HPD status check, because the > HPD may be affected by noise, once the chip detect HPD is low, the timer > register will be automatically set to 1.4ms, so the driver better set it > in each check loop. > > Thanks, > Xin > > > > > + if (ret < 0) > > > + return ret; > > > + > > > return anx7625_reg_read(ctx, ctx->i2c.rx_p0_client, SYSTEM_STSTUS); > > > } > > > > > > diff --git a/drivers/gpu/drm/bridge/analogix/anx7625.h b/drivers/gpu/drm/bridge/analogix/anx7625.h > > > index e257a84db962..14f33d6be289 100644 > > > --- a/drivers/gpu/drm/bridge/analogix/anx7625.h > > > +++ b/drivers/gpu/drm/bridge/analogix/anx7625.h > > > @@ -132,6 +132,12 @@ > > > #define I2S_SLAVE_MODE 0x08 > > > #define AUDIO_LAYOUT 0x01 > > > > > > +#define HPD_DET_TIMER_BIT0_7 0xea > > > +#define HPD_DET_TIMER_BIT8_15 0xeb > > > +#define HPD_DET_TIMER_BIT16_23 0xec > > > +/* HPD debounce time 2ms for 27M clock */ > > > +#define HPD_TIME 54000 > > > + > > > #define AUDIO_CONTROL_REGISTER 0xe6 > > > #define TDM_TIMING_MODE 0x08 > > > > > > -- > > > 2.25.1 > > > Reviewed-by: Robert Foss Applied to drm-misc-next.