linux-kernel - Re: [PATCH] spi: spi-geni-qcom: Select FIFO mode for chip select

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Message-ID: <CAD=FV=UNvsSP=ELt557e5MQ_vfeFgSYahNcR8Pykw+Kxxnd97g@mail.gmail.com>
Date:   Tue, 9 May 2023 07:25:59 -0700
From:   Doug Anderson <dianders@...omium.org>
To:     Vijaya Krishna Nivarthi <quic_vnivarth@...cinc.com>
Cc:     agross@...nel.org, andersson@...nel.org, konrad.dybcio@...aro.org,
        broonie@...nel.org, linux-arm-msm@...r.kernel.org,
        linux-spi@...r.kernel.org, linux-kernel@...r.kernel.org,
        quic_msavaliy@...cinc.com, mka@...omium.org, swboyd@...omium.org,
        quic_vtanuku@...cinc.com, quic_ptalari@...cinc.com
Subject: Re: [PATCH] spi: spi-geni-qcom: Select FIFO mode for chip select

Hi,

On Tue, May 9, 2023 at 3:01 AM Vijaya Krishna Nivarthi
<quic_vnivarth@...cinc.com> wrote:
>
> Spi geni driver switches between FIFO and DMA modes based on xfer length.
> FIFO mode relies on M_CMD_DONE_EN interrupt for completion while DMA mode
> relies on XX_DMA_DONE.
> During dynamic switching, if FIFO mode is chosen, FIFO related interrupts
> are enabled and DMA related interrupts are disabled. And viceversa.
> Chip select shares M_CMD_DONE_EN interrupt with FIFO to check completion.
> Now, if a chip select operation is preceded by a DMA xfer, M_CMD_DONE_EN
> interrupt would have been disabled and hence it will never receive one
> resulting in timeout.
>
> For chip select, in addition to setting the xfer mode to FIFO,
> select_mode() to FIFO so that required interrupts are enabled.
>
> Fixes: e5f0dfa78ac7 ("spi: spi-geni-qcom: Add support for SE DMA mode")
> Suggested-by: Praveen Talari <quic_ptalari@...cinc.com>
> Signed-off-by: Vijaya Krishna Nivarthi <quic_vnivarth@...cinc.com>
> ---
>  drivers/spi/spi-geni-qcom.c | 2 ++
>  1 file changed, 2 insertions(+)

Reviewed-by: Douglas Anderson <dianders@...omium.org>