linux-kernel - RE: [PATCH v4 08/15] dmaengine: dw-axi-dmac: Support of_dma_controller

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Date:   Fri, 20 Nov 2020 00:47:52 +0000
From:   "Sia, Jee Heng" <jee.heng.sia@...el.com>
To:     Eugeniy Paltsev <Eugeniy.Paltsev@...opsys.com>,
        "vkoul@...nel.org" <vkoul@...nel.org>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>
CC:     "andriy.shevchenko@...ux.intel.com" 
        <andriy.shevchenko@...ux.intel.com>,
        "dmaengine@...r.kernel.org" <dmaengine@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>
Subject: RE: [PATCH v4 08/15] dmaengine: dw-axi-dmac: Support
 of_dma_controller_register()



> -----Original Message-----
> From: Eugeniy Paltsev <Eugeniy.Paltsev@...opsys.com>
> Sent: 19 November 2020 8:10 AM
> To: Sia, Jee Heng <jee.heng.sia@...el.com>; vkoul@...nel.org; robh+dt@...nel.org
> Cc: andriy.shevchenko@...ux.intel.com; dmaengine@...r.kernel.org; linux-
> kernel@...r.kernel.org; devicetree@...r.kernel.org
> Subject: Re: [PATCH v4 08/15] dmaengine: dw-axi-dmac: Support
> of_dma_controller_register()
> 
> Hi Sia,
> 
> > Subject: [PATCH v4 08/15] dmaengine: dw-axi-dmac: Support
> > of_dma_controller_register()
> >
> > Add support for of_dma_controller_register() so that DMA clients can
> > pass in device handshake number to the AxiDMA driver.
> >
> > DMA clients shall code the device handshake number in the Device tree.
> > When DMA activities are needed, DMA clients shall invoke OF helper
> > function to pass in the device handshake number to the AxiDMA.
> >
> > Without register to the of_dma_controller_register(), data transfer
> > between memory to device and device to memory operations would failed.
> >
> > Reviewed-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> > Signed-off-by: Sia Jee Heng <jee.heng.sia@...el.com>
> > ---
> >  .../dma/dw-axi-dmac/dw-axi-dmac-platform.c    | 26 +++++++++++++++++++
> >  drivers/dma/dw-axi-dmac/dw-axi-dmac.h         |  1 +
> >  2 files changed, 27 insertions(+)
> >
> > diff --git a/drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c
> > b/drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c
> > index b5f92f9cb2bc..72871b8738be 100644
> > --- a/drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c
> > +++ b/drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c
> > @@ -20,6 +20,7 @@
> >  #include <linux/kernel.h>
> >  #include <linux/module.h>
> >  #include <linux/of.h>
> > +#include <linux/of_dma.h>
> >  #include <linux/platform_device.h>
> >  #include <linux/pm_runtime.h>
> >  #include <linux/property.h>
> > @@ -1044,6 +1045,22 @@ static int __maybe_unused
> axi_dma_runtime_resume(struct device *dev)
> >         return axi_dma_resume(chip);
> >  }
> >
> > +static struct dma_chan *dw_axi_dma_of_xlate(struct of_phandle_args
> *dma_spec,
> > +                                           struct of_dma *ofdma) {
> > +       struct dw_axi_dma *dw = ofdma->of_dma_data;
> > +       struct axi_dma_chan *chan;
> > +       struct dma_chan *dchan;
> > +
> > +       dchan = dma_get_any_slave_channel(&dw->dma);
> > +       if (!dchan)
> > +               return NULL;
> > +
> > +       chan = dchan_to_axi_dma_chan(dchan);
> > +       chan->hw_hs_num = dma_spec->args[0];
> > +       return dchan;
> > +}
> > +
> >  static int parse_device_properties(struct axi_dma_chip *chip)  {
> >         struct device *dev = chip->dev; @@ -1233,6 +1250,13 @@ static
> > int dw_probe(struct platform_device *pdev)
> >         if (ret)
> >                 goto err_pm_disable;
> >
> > +       /* Register with OF helpers for DMA lookups */
> > +       ret = of_dma_controller_register(pdev->dev.of_node,
> > +                                        dw_axi_dma_of_xlate, dw);
> > +       if (ret < 0)
> > +               dev_warn(&pdev->dev,
> > +                        "Failed to register OF DMA controller,
> > + fallback to MEM_TO_MEM mode\n");
> > +
> >         dev_info(chip->dev, "DesignWare AXI DMA Controller, %d channels\n",
> >                  dw->hdata->nr_channels);
> >
> > @@ -1266,6 +1290,8 @@ static int dw_remove(struct platform_device
> > *pdev)
> >
> >         devm_free_irq(chip->dev, chip->irq, chip);
> >
> > +       of_dma_controller_free(chip->dev->of_node);
> > +
> >         list_for_each_entry_safe(chan, _chan, &dw->dma.channels,
> >                         vc.chan.device_node) {
> >                 list_del(&chan->vc.chan.device_node);
> > diff --git a/drivers/dma/dw-axi-dmac/dw-axi-dmac.h
> > b/drivers/dma/dw-axi-dmac/dw-axi-dmac.h
> > index a26b0a242a93..651874e5c88f 100644
> > --- a/drivers/dma/dw-axi-dmac/dw-axi-dmac.h
> > +++ b/drivers/dma/dw-axi-dmac/dw-axi-dmac.h
> > @@ -37,6 +37,7 @@ struct axi_dma_chan {
> >         struct axi_dma_chip             *chip;
> >         void __iomem                    *chan_regs;
> >         u8                              id;
> > +       u8                              hw_hs_num;
> Just a nitpick: 'hw_hs_num' sounds quite obfuscated. Could it be
> 'hw_handshake_num' for example?
[>>] OK, will rename it to hw_handshake_num .
> 
> >         atomic_t                        descs_allocated;
> >
> >         struct dma_pool                 *desc_pool;
> > --
> > 2.18.0
> >