Re: [PATCH 1/6] media: mach-pxa: Register the camera sensor fixed-rate clock

[Petr Cvek <petrcvekcz@gmail.com>]

Dne 04. 01. 21 v 17:57 Ezequiel Garcia napsal(a):
> The pxa-camera capture driver currently registers a v4l2-clk
> clock, named "mclk", to represent the mt9m111 sensor clock.
> 
> Register a proper fixed-rate clock using the generic clock framework,
> which will allow to remove the v4l2-clk clock in the pxa-camera
> driver in a follow-up commit.
> 

BTW the mclk output to a sensor is actually a variable rate, divided from lcdclk (which can be changed too). PXA camera driver  is using variable pcdev->mclk_divisor to generate the mclk from lcdclk. 

The rate change is done in pxa_camera_activate():

https://elixir.bootlin.com/linux/v5.11-rc2/source/drivers/media/platform/pxa_camera.c#L1136

	__raw_writel(pcdev->mclk_divisor | cicr4, pcdev->base + CICR4);

Would it be possible to register a correct clock type with possibility to change the divisor by the standard way?

Petr


> Cc: Arnd Bergmann <arnd@arndb.de>
> Cc: Robert Jarzmik <robert.jarzmik@free.fr>
> Signed-off-by: Ezequiel Garcia <ezequiel@collabora.com>
> ---
>  arch/arm/mach-pxa/devices.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/arch/arm/mach-pxa/devices.c b/arch/arm/mach-pxa/devices.c
> index 524d6093e0c7..09b8495f3fd9 100644
> --- a/arch/arm/mach-pxa/devices.c
> +++ b/arch/arm/mach-pxa/devices.c
> @@ -4,6 +4,7 @@
>  #include <linux/init.h>
>  #include <linux/platform_device.h>
>  #include <linux/clkdev.h>
> +#include <linux/clk-provider.h>
>  #include <linux/dma-mapping.h>
>  #include <linux/dmaengine.h>
>  #include <linux/spi/pxa2xx_spi.h>
> @@ -634,6 +635,13 @@ static struct platform_device pxa27x_device_camera = {
>  
>  void __init pxa_set_camera_info(struct pxacamera_platform_data *info)
>  {
> +	struct clk *mclk;
> +
> +	/* Register a fixed-rate clock for camera sensors. */
> +	mclk = clk_register_fixed_rate(NULL, "pxa_camera_clk", NULL, 0,
> +					     info->mclk_10khz * 10000);
> +	if (!IS_ERR(mclk))
> +		clkdev_create(mclk, "mclk", NULL);
>  	pxa_register_device(&pxa27x_device_camera, info);
>  }
>  
>