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From:   Doug Anderson <dianders@chromium.org>
Date:   Thu, 20 Apr 2023 11:09:21 -0700
Message-ID: <CAD=FV=UkSQUSkY0UsU=s=PhXYRCrh-0TWM4K7FRfymTtL+MbcQ@mail.gmail.com>
Subject: Re: [PATCH v4 5/5] spi: spi-qcom-qspi: Add DMA mode support
To:     Vijaya Krishna Nivarthi <quic_vnivarth@quicinc.com>
Cc:     agross@kernel.org, andersson@kernel.org, konrad.dybcio@linaro.org,
        broonie@kernel.org, robh+dt@kernel.org,
        krzysztof.kozlowski+dt@linaro.org,
        cros-qcom-dts-watchers@chromium.org, linux-arm-msm@vger.kernel.org,
        linux-spi@vger.kernel.org, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org, quic_msavaliy@quicinc.com,
        mka@chromium.org, swboyd@chromium.org, quic_vtanuku@quicinc.com
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Hi,

On Thu, Apr 20, 2023 at 6:13=E2=80=AFAM Vijaya Krishna Nivarthi
<quic_vnivarth@quicinc.com> wrote:
>
> @@ -528,6 +760,7 @@ static int qcom_qspi_probe(struct platform_device *pd=
ev)
>         master->prepare_message =3D qcom_qspi_prepare_message;
>         master->transfer_one =3D qcom_qspi_transfer_one;
>         master->handle_err =3D qcom_qspi_handle_err;
> +       master->can_dma =3D qcom_qspi_can_dma;

One extra comment: it might be worth adding something like this (untested):

if (of_property_read_bool(np, "iommus"))
  master->can_dma =3D qcom_qspi_can_dma;

That will have the dual benefit of making old device trees work (which
we're supposed to to if possible) and also making it easier to land
these changes. Without something like that then I think transfers will
fail for anyone who pulls in the SPI tree but not the Qualcomm DT
tree.