linux-kernel - Re: [PATCH v7 08/11] dmaengine: dw: Add dummy device

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Message-ID: <20200710094510.j6ugxygkadxex53c@mobilestation>
Date:   Fri, 10 Jul 2020 12:45:10 +0300
From:   Serge Semin <Sergey.Semin@...kalelectronics.ru>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
CC:     Vinod Koul <vkoul@...nel.org>, Viresh Kumar <vireshk@...nel.org>,
        Dan Williams <dan.j.williams@...el.com>,
        Alexey Malahov <Alexey.Malahov@...kalelectronics.ru>,
        Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
        Arnd Bergmann <arnd@...db.de>,
        Rob Herring <robh+dt@...nel.org>, <linux-mips@...r.kernel.org>,
        <devicetree@...r.kernel.org>, <dmaengine@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v7 08/11] dmaengine: dw: Add dummy device_caps callback

On Fri, Jul 10, 2020 at 11:51:23AM +0300, Andy Shevchenko wrote:
> On Fri, Jul 10, 2020 at 01:45:47AM +0300, Serge Semin wrote:
> > Since some DW DMA controllers (like one installed on Baikal-T1 SoC) may
> > have non-uniform DMA capabilities per device channels, let's add
> > the DW DMA specific device_caps callback to expose that specifics up to
> > the DMA consumer. It's a dummy function for now. We'll fill it in with
> > capabilities overrides in the next commits.
> 

> Just a reminder (mainly to Vinod) of my view to this.
> Unneeded churn, should be folded to patch 9.

Just to remind (mainly to Vinod). That's Andy's bikeshedding.
This isn't a churn, since it's totally normal to design the patchset in this way:
introduce a callback, then fill it in with functionality.

-Sergey

> 
> > Signed-off-by: Serge Semin <Sergey.Semin@...kalelectronics.ru>
> > Cc: Alexey Malahov <Alexey.Malahov@...kalelectronics.ru>
> > Cc: Thomas Bogendoerfer <tsbogend@...ha.franken.de>
> > Cc: Arnd Bergmann <arnd@...db.de>
> > Cc: Rob Herring <robh+dt@...nel.org>
> > Cc: linux-mips@...r.kernel.org
> > Cc: devicetree@...r.kernel.org
> > 
> > ---
> > 
> > Changelog v3:
> > - This is a new patch created as a result of the discussion with Vinud and
> >   Andy in the framework of DW DMA burst and LLP capabilities.
> > ---
> >  drivers/dma/dw/core.c | 6 ++++++
> >  1 file changed, 6 insertions(+)
> > 
> > diff --git a/drivers/dma/dw/core.c b/drivers/dma/dw/core.c
> > index fb95920c429e..ceded21537e2 100644
> > --- a/drivers/dma/dw/core.c
> > +++ b/drivers/dma/dw/core.c
> > @@ -1049,6 +1049,11 @@ static void dwc_free_chan_resources(struct dma_chan *chan)
> >  	dev_vdbg(chan2dev(chan), "%s: done\n", __func__);
> >  }
> >  
> > +static void dwc_caps(struct dma_chan *chan, struct dma_slave_caps *caps)
> > +{
> > +
> > +}
> > +
> >  int do_dma_probe(struct dw_dma_chip *chip)
> >  {
> >  	struct dw_dma *dw = chip->dw;
> > @@ -1214,6 +1219,7 @@ int do_dma_probe(struct dw_dma_chip *chip)
> >  	dw->dma.device_prep_dma_memcpy = dwc_prep_dma_memcpy;
> >  	dw->dma.device_prep_slave_sg = dwc_prep_slave_sg;
> >  
> > +	dw->dma.device_caps = dwc_caps;
> >  	dw->dma.device_config = dwc_config;
> >  	dw->dma.device_pause = dwc_pause;
> >  	dw->dma.device_resume = dwc_resume;
> > -- 
> > 2.26.2
> > 
> 
> -- 
> With Best Regards,
> Andy Shevchenko
> 
>