On Mon, 2021-01-18 at 18:36 +0200, Sakari Ailus wrote:
> Hi Ezequiel,
>
> Thanks for the patch.
>
> On Tue, Jan 12, 2021 at 04:49:14PM -0300, Ezequiel Garcia wrote:
> > 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.
>
> Where is the clock generated?
>
> If it's the same device, shouldn't it be registered in the pxa_camera
> driver?
>
Apparently, as Petr explained, the PXA camera controller
can provide a clock.
However, it seems to me this is not necesarily the only
way to provide a clock to a sensor, is it?
Moreover, doing the proper clock conversion in the PXA driver
doesn't seem trivial and I don't have hardware to test it.
I'd rather keep things simple, and just register a fixed-rate
clock at mach-pxa level, which will be removed anyway
once these non-DT platforms are finally converted to DT
or dropped.
This way is at least a tiny bit less ugly than the current
dummy v4l2-clk.
Thanks,
Ezequiel
> >
> > Signed-off-by: Ezequiel Garcia <ezequiel@xxxxxxxxxxxxx>
> > Acked-by: Arnd Bergmann <arnd@xxxxxxxx> (for arch/arm/mach-*/)
> > ---
> > Quoting Arnd:
> > """
> > If there are no objections to the change itself, please take it through
> > the v4l2 git tree.
> > """
> >
> > 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);
> > }
> >
>
