From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail-by2on0099.outbound.protection.outlook.com ([207.46.100.99]:4416 "EHLO na01-by2-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752390AbcFVLbC (ORCPT ); Wed, 22 Jun 2016 07:31:02 -0400 From: Dragos Bogdan To: Hans Verkuil , Mauro Carvalho Chehab CC: Lars-Peter Clausen , , Dragos Bogdan Subject: [PATCH v3] [media] adv7604: Add support for hardware reset Date: Wed, 22 Jun 2016 14:30:42 +0300 Message-ID: <1466595042-3649-1-git-send-email-dragos.bogdan@analog.com> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-media-owner@vger.kernel.org List-ID: The part can be reset by a low pulse on the RESET pin (i.e. a hardware reset) with a minimum width of 5 ms. It is recommended to wait 5 ms after the low pulse before an I2C write is performed to the part. For safety reasons, the delays will be between 5 and 10 ms. The RESET pin can be tied high, so the GPIO is optional. Signed-off-by: Dragos Bogdan Reviewed-by: Lars-Peter Clausen Acked-by: Laurent Pinchart --- Changes since v2: - adv76xx_reset() is now a void function (it always returned 0). Changes since v1: - Replace mdelay() with usleep_range(); - Limit the comments to 75 characters per line. drivers/media/i2c/adv7604.c | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) diff --git a/drivers/media/i2c/adv7604.c b/drivers/media/i2c/adv7604.c index 41a1bfc..ab4f933 100644 --- a/drivers/media/i2c/adv7604.c +++ b/drivers/media/i2c/adv7604.c @@ -164,6 +164,7 @@ struct adv76xx_state { struct adv76xx_platform_data pdata; struct gpio_desc *hpd_gpio[4]; + struct gpio_desc *reset_gpio; struct v4l2_subdev sd; struct media_pad pads[ADV76XX_PAD_MAX]; @@ -2996,6 +2997,19 @@ static int configure_regmaps(struct adv76xx_state *state) return 0; } +static void adv76xx_reset(struct adv76xx_state *state) +{ + if (state->reset_gpio) { + /* ADV76XX can be reset by a low reset pulse of minimum 5 ms. */ + gpiod_set_value_cansleep(state->reset_gpio, 0); + usleep_range(5000, 10000); + gpiod_set_value_cansleep(state->reset_gpio, 1); + /* It is recommended to wait 5 ms after the low pulse before */ + /* an I2C write is performed to the ADV76XX. */ + usleep_range(5000, 10000); + } +} + static int adv76xx_probe(struct i2c_client *client, const struct i2c_device_id *id) { @@ -3059,6 +3073,12 @@ static int adv76xx_probe(struct i2c_client *client, if (state->hpd_gpio[i]) v4l_info(client, "Handling HPD %u GPIO\n", i); } + state->reset_gpio = devm_gpiod_get_optional(&client->dev, "reset", + GPIOD_OUT_HIGH); + if (IS_ERR(state->reset_gpio)) + return PTR_ERR(state->reset_gpio); + + adv76xx_reset(state); state->timings = cea640x480; state->format = adv76xx_format_info(state, MEDIA_BUS_FMT_YUYV8_2X8); -- 2.1.4