Re: [PATCH v4 3/4] media: raspberrypi: Add support for RP1-CFE

[Tomi Valkeinen]

Hi Laurent, Jacopo,

On 09/09/2024 08:08, Tomi Valkeinen wrote:
> Hi,
>
> On 05/09/2024 14:11, Laurent Pinchart wrote:
> > On Thu, Sep 05, 2024 at 06:50:48PM +0800, kernel test robot wrote:
> > > Hi Tomi,
> > >
> > > kernel test robot noticed the following build warnings:
> > >
> > > [auto build test WARNING on 431c1646e1f86b949fa3685efc50b660a364c2b6]
> > >
> > > url:    https://github.com/intel-lab-lkp/linux/commits/Tomi- 
> > > Valkeinen/media-uapi-Add-meta-formats-for-PiSP-FE-config-and- 
> > > stats/20240904-192729
> > > base:   431c1646e1f86b949fa3685efc50b660a364c2b6
> > > patch link:    https://lore.kernel.org/r/20240904-rp1-cfe-v4-3- 
> > > f1b5b3d69c81%40ideasonboard.com
> > > patch subject: [PATCH v4 3/4] media: raspberrypi: Add support for 
> > > RP1-CFE
> > > config: m68k-allmodconfig (https://download.01.org/0day-ci/ 
> > > archive/20240905/202409051822.ZzUGw3XQ-lkp@xxxxxxxxx/config)
> > > compiler: m68k-linux-gcc (GCC) 14.1.0
> > > reproduce (this is a W=1 build): (https://download.01.org/0day-ci/ 
> > > archive/20240905/202409051822.ZzUGw3XQ-lkp@xxxxxxxxx/reproduce)
> > >
> > > If you fix the issue in a separate patch/commit (i.e. not just a new 
> > > version of
> > > the same patch/commit), kindly add following tags
> > > | Reported-by: kernel test robot <lkp@xxxxxxxxx>
> > > | Closes: https://lore.kernel.org/oe-kbuild- 
> > > all/202409051822.ZzUGw3XQ-lkp@xxxxxxxxx/
> > >
> > > All warnings (new ones prefixed by >>):
> > >
> > > > > drivers/media/platform/raspberrypi/rp1-cfe/cfe.c:2445:12: warning: 
> > > > > 'cfe_runtime_resume' defined but not used [-Wunused-function]
> > >      2445 | static int cfe_runtime_resume(struct device *dev)
> > >           |            ^~~~~~~~~~~~~~~~~~
> > > > > drivers/media/platform/raspberrypi/rp1-cfe/cfe.c:2435:12: warning: 
> > > > > 'cfe_runtime_suspend' defined but not used [-Wunused-function]
> > >      2435 | static int cfe_runtime_suspend(struct device *dev)
> > >           |            ^~~~~~~~~~~~~~~~~~~
> > > vim +/cfe_runtime_resume +2445 drivers/media/platform/raspberrypi/ 
> > > rp1-cfe/cfe.c
> >
> > The recommended way to fix this is to switch from SET_RUNTIME_PM_OPS()
> > to RUNTIME_PM_OPS() and use pm_ptr() to set .driver.pm. This being said,
> > the driver won't work on a kernel with !CONFIG_PM given how you
> > implemented probe() and remove().
> >
> > The pisp-be driver suffered from the same issue and Jacopo fixed it in
> > the last version. You can have a look at implement something similar.
>
> I can't right away think of any reason to not just depend on CONFIG_PM 
> and be done with it without any tricks. Do you know if there's a reason?

Also, I don't think pisp-be is correct. It just calls 
pispbe_runtime_resume() in probe() to wake the IP up (which only enables 
pisp clock), without telling the runtime PM about it. This means the 
parent device and the suppliers may not be powered up.

 Tomi