[PATCH 1/3] media: atmel-isi: move the peripheral clock to start/stop_stream() function

Laurent Pinchart
2015-03-05T10:39:42Z

Hi Josh,

Thank you for the patch.

On Thursday 05 March 2015 13:00:59 Josh Wu wrote:
> As the clock_start/stop() use to control the mclk for the sensor not the
> ISI peripheral clock.
> So we move them to start/stop_stream() function.

Then the driver will access registers with the peripheral clock disabled, for
instance in isi_camera_set_fmt() (calling configure_geometry),
isi_camera_set_bus_param() or atmel_isi_probe(). Isn't that a problem ? Or are
all registers guaranteed to be accessible (and retained) when the clock is
disabled ?

> Signed-off-by: Josh Wu <josh.wu@atmel.com>
> ---
>
> drivers/media/platform/soc_camera/atmel-isi.c | 12 ++++++------
> 1 file changed, 6 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/media/platform/soc_camera/atmel-isi.c
> b/drivers/media/platform/soc_camera/atmel-isi.c index 1208818..eb179e7
> 100644
> --- a/drivers/media/platform/soc_camera/atmel-isi.c
> +++ b/drivers/media/platform/soc_camera/atmel-isi.c
> @@ -386,6 +386,10 @@ static int start_streaming(struct vb2_queue *vq,
> unsigned int count) struct atmel_isi *isi = ici->priv;
> int ret;
>
> + ret = clk_prepare_enable(isi->pclk);
> + if (ret)
> + return ret;
> +
> /* Reset ISI */
> ret = atmel_isi_wait_status(isi, WAIT_ISI_RESET);
> if (ret < 0) {
> @@ -445,6 +449,8 @@ static void stop_streaming(struct vb2_queue *vq)
> ret = atmel_isi_wait_status(isi, WAIT_ISI_DISABLE);
> if (ret < 0)
> dev_err(icd->parent, "Disable ISI timed out\n");
> +
> + clk_disable_unprepare(isi->pclk);
> }
>
> static struct vb2_ops isi_video_qops = {
> @@ -723,14 +729,9 @@ static int isi_camera_clock_start(struct
> soc_camera_host *ici) struct atmel_isi *isi = ici->priv;
> int ret;
>
> - ret = clk_prepare_enable(isi->pclk);
> - if (ret)
> - return ret;
> -
> if (!IS_ERR(isi->mck)) {
> ret = clk_prepare_enable(isi->mck);
> if (ret) {
> - clk_disable_unprepare(isi->pclk);
> return ret;
> }
> }
> @@ -745,7 +746,6 @@ static void isi_camera_clock_stop(struct soc_camera_host
> *ici)
>
> if (!IS_ERR(isi->mck))
> clk_disable_unprepare(isi->mck);
> - clk_disable_unprepare(isi->pclk);
> }
>
> static unsigned int isi_camera_poll(struct file *file, poll_table *pt)

--
Regards,

Laurent Pinchart