Re: [PATCH] video: fbdev: fsl: fix kernel crash when diu_ops is not implemented

[Scott Wood <scottwood@freescale.com>]

On Tue, 2015-11-24 at 11:12 -0500, Timur Tabi wrote:
>  On Tue, Nov 24, 2015 at 1:27 AM, Dongsheng Wang
> <dongsheng.wang@freescale.com> wrote:
> > @@ -1697,6 +1700,9 @@ static int fsl_diu_probe(struct platform_device
> > *pdev)
> >         unsigned int i;
> >         int ret;
> > 
> > +       if (!diu_ops.set_pixel_clock)
> > +               return -ENODEV;
> > +
> >         data = dmam_alloc_coherent(&pdev->dev, sizeof(struct
> > fsl_diu_data),
> >                                    &dma_addr, GFP_DMA | __GFP_ZERO);
> >         if (!data)
> 
> This doesn't make any sense.  If set_pixel_clock() is not defined,
> then the whole driver aborts the probe.

That's what this patch is trying to accomplish.  Currently it crashes instead.

>   When could that ever happen?
> If the platform code does not exist, then don't let the driver be
> probed.

How do you propose to accomplish that other than with such a check?

-Scott