linux-kernel - RE: [PATCH v20 2/2] dmaengine: tegra: Add tegra gpcdma driver

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Date:   Wed, 23 Feb 2022 03:49:09 +0000
From:   Akhil R <akhilrajeev@...dia.com>
To:     Nathan Chancellor <nathan@...nel.org>
CC:     "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "dmaengine@...r.kernel.org" <dmaengine@...r.kernel.org>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Krishna Yarlagadda <kyarlagadda@...dia.com>,
        Laxman Dewangan <ldewangan@...dia.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-tegra@...r.kernel.org" <linux-tegra@...r.kernel.org>,
        "p.zabel@...gutronix.de" <p.zabel@...gutronix.de>,
        Rajesh Gumasta <rgumasta@...dia.com>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "thierry.reding@...il.com" <thierry.reding@...il.com>,
        "vkoul@...nel.org" <vkoul@...nel.org>,
        Pavan Kunapuli <pkunapuli@...dia.com>
Subject: RE: [PATCH v20 2/2] dmaengine: tegra: Add tegra gpcdma driver

> Hi Akhil,
> 
> On Mon, Feb 21, 2022 at 09:09:34PM +0530, Akhil R wrote:
> > Adding GPC DMA controller driver for Tegra. The driver supports dma
> > transfers between memory to memory, IO peripheral to memory and memory
> > to IO peripheral.
> >
> > Co-developed-by: Pavan Kunapuli <pkunapuli@...dia.com>
> > Signed-off-by: Pavan Kunapuli <pkunapuli@...dia.com>
> > Co-developed-by: Rajesh Gumasta <rgumasta@...dia.com>
> > Signed-off-by: Rajesh Gumasta <rgumasta@...dia.com>
> > Signed-off-by: Akhil R <akhilrajeev@...dia.com>
> > Reviewed-by: Jon Hunter <jonathanh@...dia.com>
> > Reviewed-by: Dmitry Osipenko <digetx@...il.com>
> > ---
> >  drivers/dma/Kconfig            |   11 +
> >  drivers/dma/Makefile           |    1 +
> >  drivers/dma/tegra186-gpc-dma.c | 1507
> > ++++++++++++++++++++++++++++++++
> >  3 files changed, 1519 insertions(+)
> >  create mode 100644 drivers/dma/tegra186-gpc-dma.c
> 
> <snip>
> 
> > +static const struct __maybe_unused dev_pm_ops tegra_dma_dev_pm_ops =
> > +{
> 
> The __maybe_unused cannot split the type ("struct dev_pm_ops") otherwise it
> causes a clang warning:
> 
> https://lore.kernel.org/r/202202221207.lQ53BwKp-lkp@intel.com/
> 
> static const struct dev_pm_ops tegra_dma_dev_pm_ops __maybe_unused = {
> 
> would look a litle better I think. However, is this attribute even needed? The
> variable is unconditionally used below, so there should be no warning about it
> being unused?
> 
> Cheers,
> Nathan
> 
> > +     SET_SYSTEM_SLEEP_PM_OPS(tegra_dma_pm_suspend,
> > +tegra_dma_pm_resume) };
> > +
> > +static struct platform_driver tegra_dma_driver = {
> > +     .driver = {
> > +             .name   = "tegra-gpcdma",
> > +             .pm     = &tegra_dma_dev_pm_ops,
> > +             .of_match_table = tegra_dma_of_match,
> > +     },
> > +     .probe          = tegra_dma_probe,
> > +     .remove         = tegra_dma_remove,
> > +};
> > +
> > +module_platform_driver(tegra_dma_driver);
> > +
> > +MODULE_DESCRIPTION("NVIDIA Tegra GPC DMA Controller driver");
> > +MODULE_AUTHOR("Pavan Kunapuli <pkunapuli@...dia.com>");
> > +MODULE_AUTHOR("Rajesh Gumasta <rgumasta@...dia.com>");
> > +MODULE_LICENSE("GPL");
> > --
> > 2.17.1
> >
> >

Hi Nathan,

Thanks. Will update the same.

I am getting notification for the below warning also.

>> drivers/dma/tegra186-gpc-dma.c:898:53: warning: shift count >= width of type [-Wshift-count-overflow]
                           FIELD_PREP(TEGRA_GPCDMA_HIGH_ADDR_DST_PTR, (dest >> 32));
https://lore.kernel.org/all/202202230559.bLOEMEUh-lkp@intel.com/

I suppose, this is because it is compiled against a different ARCH other than arm64.
For arm64, the dma_addr_t is 64 bytes, and this warning does not occur.
Could this be ignored for now? If not, could you suggest a fix, if possible?

Thanks,
Akhil