linux-kernel - Re: [RESEND PATCH v2] dmaengine: mxs: fix driver registering

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Date:   Thu, 9 Jun 2022 08:18:36 +0200
From:   Michael Nazzareno Trimarchi <michael@...rulasolutions.com>
To:     Vinod Koul <vkoul@...nel.org>
Cc:     Dario Binacchi <dario.binacchi@...rulasolutions.com>,
        linux-kernel@...r.kernel.org,
        Amarula patchwork <linux-amarula@...rulasolutions.com>,
        stable@...r.kernel.org, Fabio Estevam <festevam@...il.com>,
        NXP Linux Team <linux-imx@....com>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        Shawn Guo <shawnguo@...nel.org>, dmaengine@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [RESEND PATCH v2] dmaengine: mxs: fix driver registering

Hi Vinod

On Thu, Jun 9, 2022 at 8:07 AM Vinod Koul <vkoul@...nel.org> wrote:
>
> On 09-06-22, 08:01, Michael Nazzareno Trimarchi wrote:
> > Hi
> >
> > On Thu, Jun 9, 2022 at 7:48 AM Vinod Koul <vkoul@...nel.org> wrote:
> > >
> > > On 07-06-22, 11:58, Dario Binacchi wrote:
> > > > Driver registration fails on SOC imx8mn as its supplier, the clock
> > > > control module, is not ready. Since platform_driver_probe(), as
> > > > reported by its description, is incompatible with deferred probing,
> > > > we have to use platform_driver_register().
> > > >
> > > > Fixes: a580b8c5429a ("dmaengine: mxs-dma: add dma support for i.MX23/28")
> > > > Co-developed-by: Michael Trimarchi <michael@...rulasolutions.com>
> > > > Signed-off-by: Michael Trimarchi <michael@...rulasolutions.com>
> > > > Signed-off-by: Dario Binacchi <dario.binacchi@...rulasolutions.com>
> > > > Cc: stable@...r.kernel.org
> > > >
> > > > ---
> > > >
> > > > Changes in v2:
> > > > - Add the tag "Cc: stable@...r.kernel.org" in the sign-off area.
> > > >
> > > >  drivers/dma/mxs-dma.c | 11 ++++-------
> > > >  1 file changed, 4 insertions(+), 7 deletions(-)
> > > >
> > > > diff --git a/drivers/dma/mxs-dma.c b/drivers/dma/mxs-dma.c
> > > > index 994fc4d2aca4..b8a3e692330d 100644
> > > > --- a/drivers/dma/mxs-dma.c
> > > > +++ b/drivers/dma/mxs-dma.c
> > > > @@ -670,7 +670,7 @@ static enum dma_status mxs_dma_tx_status(struct dma_chan *chan,
> > > >       return mxs_chan->status;
> > > >  }
> > > >
> > > > -static int __init mxs_dma_init(struct mxs_dma_engine *mxs_dma)
> > > > +static int mxs_dma_init(struct mxs_dma_engine *mxs_dma)
> > >
> > > why drop __init for these...?
> > >
> >
> > I think that you refer to the fact that it can not be compiled as a
> > module, am I right?
>
> It is still declared as a module_platform_driver... From changelog I can
> understand that you are changing init level from subsys to module (in
> fact clocks should be moved up as arch level and dmaengine users as
> module) ...

The way the driver was using to register was:
platform_driver_probe(&driver, driver_probe);

The function try to register the driver, one time and if the
dependences is not satisfied,
then there will not a next try, so the driver initialized that way can
not depends to anything
apart himself, or all the dependencies should be ready at the time the
driver_probe is called

>
> But why remove __init declaration from these? Whatever purpose that may
> solve needs to be documented in changelog and perhaps a different patch
>

I was thinking that driver can be compiled as module as other driver
but is bool and not tristate

Michael

>
> >
> > Michael
> >
> > > >  {
> > > >       int ret;
> > > >
> > > > @@ -741,7 +741,7 @@ static struct dma_chan *mxs_dma_xlate(struct of_phandle_args *dma_spec,
> > > >                                    ofdma->of_node);
> > > >  }
> > > >
> > > > -static int __init mxs_dma_probe(struct platform_device *pdev)
> > > > +static int mxs_dma_probe(struct platform_device *pdev)
> > > >  {
> > > >       struct device_node *np = pdev->dev.of_node;
> > > >       const struct mxs_dma_type *dma_type;
> > > > @@ -839,10 +839,7 @@ static struct platform_driver mxs_dma_driver = {
> > > >               .name   = "mxs-dma",
> > > >               .of_match_table = mxs_dma_dt_ids,
> > > >       },
> > > > +     .probe = mxs_dma_probe,
> > > >  };
> > > >
> > > > -static int __init mxs_dma_module_init(void)
> > > > -{
> > > > -     return platform_driver_probe(&mxs_dma_driver, mxs_dma_probe);
> > > > -}
> > >
> > > > -subsys_initcall(mxs_dma_module_init);
> > > > +module_platform_driver(mxs_dma_driver);
> > > > --
> > > > 2.32.0
> > >
> > > --
> > > ~Vinod
>
> --
> ~Vinod



-- 
Michael Nazzareno Trimarchi
Co-Founder & Chief Executive Officer
M. +39 347 913 2170
michael@...rulasolutions.com
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