linux-kernel - Re: [PATCH 4/7] spi: spi-geni-qcom: Add support for GPI dma

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Message-ID: <YMm7ZWXnJyb8QT1u@vkoul-mobl>
Date:   Wed, 16 Jun 2021 14:20:45 +0530
From:   Vinod Koul <vkoul@...nel.org>
To:     Mark Brown <broonie@...nel.org>
Cc:     Bjorn Andersson <bjorn.andersson@...aro.org>,
        Wolfram Sang <wsa@...nel.org>, linux-arm-msm@...r.kernel.org,
        Andy Gross <agross@...nel.org>,
        Matthias Kaehlcke <mka@...omium.org>,
        Douglas Anderson <dianders@...omium.org>,
        Sumit Semwal <sumit.semwal@...aro.org>,
        Amit Pundir <amit.pundir@...aro.org>,
        linux-spi@...r.kernel.org, linux-i2c@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 4/7] spi: spi-geni-qcom: Add support for GPI dma

Hi Mark,

On 11-01-21, 16:35, Mark Brown wrote:
> On Mon, Jan 11, 2021 at 08:46:48PM +0530, Vinod Koul wrote:
> 
> > +static int get_xfer_mode(struct spi_master *spi)
> > +{
> > +	struct spi_geni_master *mas = spi_master_get_devdata(spi);
> > +	struct geni_se *se = &mas->se;
> > +	int mode = GENI_SE_FIFO;
> 
> Why not use the core DMA mapping support?

Sorry I seemed to have missed replying to this one.

Looking at the code, that is ideal case. Only issue I can see is that
core DMA mapping device being used is incorrect. The core would use
ctlr->dev.parent which is the spi0 device here.

But in this case, that wont work. We have a parent qup device which is
the parent for both spi and dma device and needs to be used for
dma-mapping! 

If we allow drivers to set dma mapping device and use that, then I can
reuse the core. Let me know if that is agreeable to you and I can hack
this up. Maybe add a new member in spi_controller which is filled by
drivers in can_dma() callback?

Thanks
-- 
~Vinod