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Mon, 6 May 2024 13:24:40 +0000 (UTC) Received: from x1.localdomain.com (unknown [10.39.193.22]) by smtp.corp.redhat.com (Postfix) with ESMTP id 62838C13FA1; Mon, 6 May 2024 13:24:39 +0000 (UTC) From: Hans de Goede To: Sakari Ailus , Bingbu Cao , Tianshu Qiu Cc: Hans de Goede , Mauro Carvalho Chehab , linux-media@vger.kernel.org Subject: [PATCH] media: ov2740: Ensure proper reset sequence on probe() Date: Mon, 6 May 2024 15:24:38 +0200 Message-ID: <20240506132438.278920-1-hdegoede@redhat.com> Precedence: bulk X-Mailing-List: linux-media@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.8 X-LSpam-Score: -3.6 (---) X-LSpam-Report: No, score=-3.6 required=5.0 tests=ARC_SIGNED=0.001,ARC_VALID=-0.1,BAYES_00=-1.9,DKIMWL_WL_HIGH=-1,DKIM_SIGNED=0.1,DKIM_VALID=-0.1,DKIM_VALID_AU=-0.1,DMARC_PASS=-0.001,HEADER_FROM_DIFFERENT_DOMAINS=0.5,MAILING_LIST_MULTI=-1,SPF_HELO_NONE=0.001,SPF_PASS=-0.001 autolearn=ham autolearn_force=no Before this commit on probe() the driver would do: reset=1 // from probe() calling gpiod_get(GPIOD_OUT_HIGH) reset=0 // from resume() msleep(20) // from resume() So if reset was 0 before getting the GPIO the reset line would only be driven high for a very short time and sometimes there would be errors reading the id register afterwards. Add a msleep(20) after getting the reset line to ensure the sensor is properly reset: reset=1 // from probe() calling gpiod_get(GPIOD_OUT_HIGH) msleep(20) // from probe() reset=0 // from resume() msleep(20) // from resume() Signed-off-by: Hans de Goede Tested-by: Stanislaw Gruszka --- drivers/media/i2c/ov2740.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/drivers/media/i2c/ov2740.c b/drivers/media/i2c/ov2740.c index 57906df7be4e..c48dbcde9877 100644 --- a/drivers/media/i2c/ov2740.c +++ b/drivers/media/i2c/ov2740.c @@ -1333,9 +1333,16 @@ static int ov2740_probe(struct i2c_client *client) return dev_err_probe(dev, ret, "failed to check HW configuration\n"); ov2740->reset_gpio = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH); - if (IS_ERR(ov2740->reset_gpio)) + if (IS_ERR(ov2740->reset_gpio)) { return dev_err_probe(dev, PTR_ERR(ov2740->reset_gpio), "failed to get reset GPIO\n"); + } else if (ov2740->reset_gpio) { + /* + * Ensure reset is asserted for at least 20 ms before + * ov2740_resume() deasserts it. + */ + msleep(20); + } ov2740->clk = devm_clk_get_optional(dev, "clk"); if (IS_ERR(ov2740->clk))