Re: [PATCH 1/7] media: hantro: add support for reset lines

Andrzej Pietrasiewicz
2021-11-30T10:39:28Z

Hi Ezequiel,

W dniu 23.11.2021 o 19:07, Ezequiel Garcia pisze:
> Hi all,
>
> Reset logic tends to be highly integration-specific, so it  could be more robust
> to deal  with this in  the machine specific file. I have some vague recollection
> of our experience here when we  integrated vc8000 last year, but I cannot recall
> the outcome.
>

Do you mean vpu->variant->init()?

That is the very first thing we do after the devm_*() calls. So any subsequent
initialization that fails would want vpu->variant->deinit(). Maybe at this
moment handling the resets at the common level is simpler? Existing drivers
will get NULL anyway from devm_reset_control_array_get().

Regards,

Andrzej

> I'm Ccing Bob who might remember better.
>
> Thanks,
> Ezequiel
>
>
>
> El mar., nov. 23, 2021 1:46 PM, Jernej Škrabec <jernej.skrabec@gmail.com
> <mailto:jernej.skrabec@gmail.com>> escribió:
>
> Hi all,
>
> Dne torek, 23. november 2021 ob 17:36:57 CET je Andrzej Pietrasiewicz
> napisal(a):
> > Hi Dan, hi Jernej,
> >
> > W dniu 23.11.2021 o 15:59, Dan Carpenter pisze:
> > > On Tue, Nov 23, 2021 at 12:09:03PM +0100, Andrzej Pietrasiewicz wrote:
> > >>> diff --git a/drivers/staging/media/hantro/hantro_drv.c b/drivers/staging/
> media/hantro/hantro_drv.c
> > >>> index ab2467998d29..8c3de31f51b3 100644
> > >>> --- a/drivers/staging/media/hantro/hantro_drv.c
> > >>> +++ b/drivers/staging/media/hantro/hantro_drv.c
> > >>> @@ -905,6 +905,10 @@ static int hantro_probe(struct platform_device
> *pdev)
> > >>>                           return PTR_ERR(vpu->clocks[0].clk);
> > >>>           }
> > >>> + vpu->resets = devm_reset_control_array_get(&pdev->dev, false,
> true);
> > >>> + if (IS_ERR(vpu->resets))
> > >>> +         return PTR_ERR(vpu->resets);
> > >>> +
> > >>>           num_bases = vpu->variant->num_regs ?: 1;
> > >>>           vpu->reg_bases = devm_kcalloc(&pdev->dev, num_bases,
> > >>>                                         sizeof(*vpu->reg_bases),
> GFP_KERNEL);
> > >>> @@ -978,10 +982,16 @@ static int hantro_probe(struct platform_device
> *pdev)
> > >>>           pm_runtime_use_autosuspend(vpu->dev);
> > >>>           pm_runtime_enable(vpu->dev);
> > >          ^^^^^^^^^^^^^^^^^^^^^^^^^^^
> > > It looks like this is the pm stuff that we have to unwind on error
> > >
> > >>> + ret = reset_control_deassert(vpu->resets);
> > >>> + if (ret) {
> > >>> +         dev_err(&pdev->dev, "Failed to deassert resets\n");
> > >>> +         return ret;
> > >                  ^^^^^^^^^^
> > > So this return should be a goto undo_pm_stuff
> > >
> > >
> > >>> + }
> > >>> +
> > >>>           ret = clk_bulk_prepare(vpu->variant->num_clocks, vpu->clocks);
> > >>>           if (ret) {
> > >>>                   dev_err(&pdev->dev, "Failed to prepare clocks\n");
> > >>> -         return ret;
> > >
> > > And this return should also have been a goto so it's a bug in the
> > > original code.
> >
> > So we probably want a separate patch addressing that first, and then
> > the series proper on top of that.
>
> I was just about to suggest that.
>
> Other drivers usually enable PM last, so they don't have PM calls in unwind
> code. However, I think current approach is just as valid (with a fix).
>
> Best regards,
> Jernej
>
> >
> > Regards,
> >
> > Andrzej
> >
> > >
> > >>> +         goto err_rst_assert;
> > >>
> > >> Before your patch is applied if clk_bulk_prepare() fails, we
> > >> simply return on the spot. After the patch is applied not only
> > >> do you...
> > >>
> > >>>           }
> > >>>           ret = v4l2_device_register(&pdev->dev, &vpu->v4l2_dev);
> > >>> @@ -1037,6 +1047,8 @@ static int hantro_probe(struct platform_device
> *pdev)
> > >>>           v4l2_device_unregister(&vpu->v4l2_dev);
> > >>>    err_clk_unprepare:
> > >>>           clk_bulk_unprepare(vpu->variant->num_clocks, vpu->clocks);
> > >>> +err_rst_assert:
> > >>> + reset_control_assert(vpu->resets);
> > >>
> > >> ...revert the effect of reset_control_deassert(), you also...
> > >>
> > >>>           pm_runtime_dont_use_autosuspend(vpu->dev);
> > >>>           pm_runtime_disable(vpu->dev);
> > >>
> > >> ... do pm_*() stuff. Is there any reason why this is needed?
> > >
> > > So, yes, it's needed, but you're correct to spot that it's not
> > > consistent.
> > >
> > > regards,
> > > dan carpenter
> > >
> >
> >
>
>