Re: [PATCH v4 3/6] media: sun6i: Update default CSI_SCLK for A64

Maxime Ripard
2018-12-18T15:23:36Z

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On Tue, Dec 18, 2018 at 05:03:17PM +0530, Jagan Teki wrote:
> Unfortunately A64 CSI cannot work with default CSI_SCLK rate.
>
> A64 BSP is using 300MHz clock rate as default csi clock,
> so sun6i_csi require explicit change to update CSI_SCLK
> rate to 300MHZ for A64 SoC's.
>
> So, set the clk_mod to 300MHz only for A64.
>
> Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
> ---
> drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.c | 5 +++++
> 1 file changed, 5 insertions(+)
>
> diff --git a/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.c b/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.c
> index 9ff61896e4bb..91470edf7581 100644
> --- a/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.c
> +++ b/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.c
> @@ -822,6 +822,11 @@ static int sun6i_csi_resource_request(struct sun6i_csi_dev *sdev,
> return PTR_ERR(sdev->clk_mod);
> }
>
> + /* A64 require 300MHz mod clock to operate properly */
> + if (of_device_is_compatible(pdev->dev.of_node,
> + "allwinner,sun50i-a64-csi"))
> + clk_set_rate_exclusive(sdev->clk_mod, 300000000);
> +

If you're using clk_set_rate_exclusive, you need to put back the
"exclusive" reference once you're not using the clock.

Doing it here is not really optimal either, since you'll put a
constraint on the system (maintaining that clock at 300MHz), while
it's not in use.

Maxime

--
Maxime Ripard, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

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