From: Hans Verkuil <hverkuil@xs4all.nl>
To: Lubomir Rintel <lkundrak@v3.sk>,
Mauro Carvalho Chehab <mchehab@kernel.org>,
Jonathan Corbet <corbet@lwn.net>,
linux-media@vger.kernel.org
Cc: Rob Herring <robh+dt@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
James Cameron <quozl@laptop.org>, Pavel Machek <pavel@ucw.cz>,
Libin Yang <lbyang@marvell.com>,
Albert Wang <twang13@marvell.com>
Subject: Re: [PATCH v2 02/11] media: ov7670: control clock along with power
Date: Wed, 14 Nov 2018 15:35:27 +0100 [thread overview]
Message-ID: <13adbb92-1815-a7ac-f8df-6b1b05ca9527@xs4all.nl> (raw)
In-Reply-To: <20181112003520.577592-3-lkundrak@v3.sk>
On 11/12/18 01:35, Lubomir Rintel wrote:
> This provides more power saving when the sensor is off.
>
> While at that, do the delay on power/clock enable even if the sensor driver
> itself doesn't control the GPIOs. This is required for the OLPC XO-1
> platform, that lacks the proper power/reset properties in its DT, but
> needs the delay after the sensor is clocked up.
>
> Signed-off-by: Lubomir Rintel <lkundrak@v3.sk>
> ---
> drivers/media/i2c/ov7670.c | 37 +++++++++++++++++++++----------------
> 1 file changed, 21 insertions(+), 16 deletions(-)
>
> diff --git a/drivers/media/i2c/ov7670.c b/drivers/media/i2c/ov7670.c
> index d87f2362bf40..a3e72c62382c 100644
> --- a/drivers/media/i2c/ov7670.c
> +++ b/drivers/media/i2c/ov7670.c
> @@ -241,6 +241,7 @@ struct ov7670_info {
> struct v4l2_mbus_framefmt format;
> struct ov7670_format_struct *fmt; /* Current format */
> struct clk *clk;
> + int on;
> struct gpio_desc *resetb_gpio;
> struct gpio_desc *pwdn_gpio;
> unsigned int mbus_config; /* Media bus configuration flags */
> @@ -1610,15 +1611,26 @@ static int ov7670_s_power(struct v4l2_subdev *sd, int on)
> {
> struct ov7670_info *info = to_state(sd);
>
> + if (info->on == on)
> + return 0;
> +
> + if (on)
> + clk_prepare_enable(info->clk);
> + else
> + clk_disable_unprepare(info->clk);
> +
> if (info->pwdn_gpio)
> gpiod_set_value(info->pwdn_gpio, !on);
> if (on && info->resetb_gpio) {
> gpiod_set_value(info->resetb_gpio, 1);
> usleep_range(500, 1000);
> gpiod_set_value(info->resetb_gpio, 0);
> - usleep_range(3000, 5000);
> }
>
> + if (on && (info->pwdn_gpio || info->resetb_gpio || info->clk))
> + usleep_range(3000, 5000);
> +
> + info->on = on;
I assume that when powered off all control settings (brightness etc) are
lost. That means that when it is powered on you should call
v4l2_ctrl_handler_setup() to re-init the control-related registers.
The same might be the case with ov7670_set_fmt and the framerate functions.
Basically the state has to be preserved across power on -> off -> on
transitions.
Regards,
Hans
> return 0;
> }
>
> @@ -1817,24 +1829,20 @@ static int ov7670_probe(struct i2c_client *client,
> else
> return ret;
> }
> - if (info->clk) {
> - ret = clk_prepare_enable(info->clk);
> - if (ret)
> - return ret;
> + ret = ov7670_init_gpio(client, info);
> + if (ret)
> + return ret;
> +
> + ov7670_s_power(sd, 1);
>
> + if (info->clk) {
> info->clock_speed = clk_get_rate(info->clk) / 1000000;
> if (info->clock_speed < 10 || info->clock_speed > 48) {
> ret = -EINVAL;
> - goto clk_disable;
> + goto power_off;
> }
> }
>
> - ret = ov7670_init_gpio(client, info);
> - if (ret)
> - goto clk_disable;
> -
> - ov7670_s_power(sd, 1);
> -
> /* Make sure it's an ov7670 */
> ret = ov7670_detect(sd);
> if (ret) {
> @@ -1913,6 +1921,7 @@ static int ov7670_probe(struct i2c_client *client,
> if (ret < 0)
> goto entity_cleanup;
>
> + ov7670_s_power(sd, 0);
> return 0;
>
> entity_cleanup:
> @@ -1921,12 +1930,9 @@ static int ov7670_probe(struct i2c_client *client,
> v4l2_ctrl_handler_free(&info->hdl);
> power_off:
> ov7670_s_power(sd, 0);
> -clk_disable:
> - clk_disable_unprepare(info->clk);
> return ret;
> }
>
> -
> static int ov7670_remove(struct i2c_client *client)
> {
> struct v4l2_subdev *sd = i2c_get_clientdata(client);
> @@ -1934,7 +1940,6 @@ static int ov7670_remove(struct i2c_client *client)
>
> v4l2_async_unregister_subdev(sd);
> v4l2_ctrl_handler_free(&info->hdl);
> - clk_disable_unprepare(info->clk);
> media_entity_cleanup(&info->sd.entity);
> ov7670_s_power(sd, 0);
> return 0;
>
next prev parent reply other threads:[~2018-11-14 14:35 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-12 0:35 [PATCH v2 0/11] media: make Marvell camera work on DT-based OLPC XO-1.75 Lubomir Rintel
2018-11-12 0:35 ` [PATCH v2 01/11] media: ov7670: hook s_power onto v4l2 core Lubomir Rintel
2018-11-12 0:35 ` [PATCH v2 02/11] media: ov7670: control clock along with power Lubomir Rintel
2018-11-14 14:35 ` Hans Verkuil [this message]
2018-11-12 0:35 ` [PATCH v2 03/11] media: dt-bindings: marvell,mmp2-ccic: Add Marvell MMP2 camera Lubomir Rintel
2018-11-17 15:39 ` Rob Herring
2018-11-12 0:35 ` [PATCH v2 04/11] [media] marvell-ccic: fix DMA s/g desc number calculation Lubomir Rintel
2018-11-12 0:35 ` [PATCH v2 05/11] [media] marvell-ccic: don't generate EOF on parallel bus Lubomir Rintel
2018-11-12 0:35 ` [PATCH v2 06/11] Revert "[media] marvell-ccic: reset ccic phy when stop streaming for stability" Lubomir Rintel
2018-11-12 0:35 ` [PATCH v2 07/11] [media] marvell-ccic: drop unused stuff Lubomir Rintel
2018-11-12 0:35 ` [PATCH v2 08/11] [media] marvell-ccic/mmp: enable clock before accessing registers Lubomir Rintel
2018-11-12 0:35 ` [PATCH v2 09/11] [media] marvell-ccic/mmp: add devicetree support Lubomir Rintel
2018-11-12 0:35 ` [PATCH v2 10/11] [media] marvell-ccic: use async notifier to get the sensor Lubomir Rintel
2018-11-12 22:06 ` kbuild test robot
2018-11-12 0:35 ` [PATCH v2 11/11] [media] marvell-ccic: provide a clock for " Lubomir Rintel
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