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From: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Date: Thu, 7 Mar 2024 16:45:50 +0200
Message-ID: <CAA8EJprky=tFjJbGTBL7+9E=kqxQKjxB_RcmzHUt31GqUVfNmQ@mail.gmail.com>
Subject: Re: [PATCH v2] i2c: i2c-qcom-geni: Parse Error correctly in i2c GSI mode
To: Mukesh Kumar Savaliya <quic_msavaliy@quicinc.com>
Cc: konrad.dybcio@linaro.org, bjorn.andersson@linaro.org, vkoul@kernel.org, 
	andi.shyti@kernel.org, wsa@kernel.org, linux-arm-msm@vger.kernel.org, 
	dmaengine@vger.kernel.org, linux-kernel@vger.kernel.org, 
	linux-i2c@vger.kernel.org, quic_vdadhani@quicinc.com
Content-Type: text/plain; charset="UTF-8"

On Thu, 7 Mar 2024 at 15:46, Mukesh Kumar Savaliya
<quic_msavaliy@quicinc.com> wrote:
>
>
>
>
> On 3/7/2024 3:23 PM, Dmitry Baryshkov wrote:
> > On Thu, 7 Mar 2024 at 11:36, Mukesh Kumar Savaliya
> > <quic_msavaliy@quicinc.com> wrote:
> >>
> >> We are seeing transfer failure instead of NACK error for simple
> >> device scan test.Ideally it should report exact error like NACK
> >> if device is not present.
> >>
> >> We may also expect errors like BUS_PROTO or ARB_LOST, hence we are
> >> adding such error support in GSI mode and reporting it accordingly
> >> by adding respective error logs.
> >
> > Please take a look at the
> > Documentation/process/submitting-patches.rst. This is not the expected
> > style of commit messages.
> >
>
> Thanks Dmitry ! Gone through the link and tried to align to the
> guidance. I will be adding into the actual upload in V3.

Let me quote the relevant part for you:

Describe your changes in imperative mood, e.g. "make xyzzy do frotz"
instead of "[This patch] makes xyzzy do frotz" or "[I] changed xyzzy
to do frotz", as if you are giving orders to the codebase to change
its behaviour.

>
> When we run scan test for i2c devices, we see transfer failures instead
> of NACK. This is wrong because there is no data transfer failure but
> it's a slave response to the i2c master controller.
>
> This change correctly identifies NACK error. Also adds support for other
> protocol errors like BUS_PROTO and ARB_LOST. This helps to exactly know
> the response on the bus.
>
> Function geni_i2c_gpi_xfer() gets called for any i2c GSI mode transfer
> and waits for the response as success OR failure. If slave is not
> present OR NACKing, GSI generates an error interrupt which calls ISR and
> it further calls gpi_process_xfer_compl_event(). Now
> dmaengine_desc_callback_invoke() will call i2c_gpi_cb_result() where we
> have added parsing status parameters to identify respective errors.
>
> >>
> >> During geni_i2c_gpi_xfer(), we should expect callback param as a
> >> transfer result. For that we have added a new structure named
> >> gpi_i2c_result, which will store xfer result.
> >>
> >> Upon receiving an interrupt, gpi_process_xfer_compl_event() will
> >> store transfer result into status variable and then call the
> >> dmaengine_desc_callback_invoke(). Hence i2c_gpi_cb_result() can
> >> parse the respective errors.
> >>
> >> while parsing error from the status param, use FIELD_GET with the
> >
> > Sentences start with the uppercase letter.
>
> Sure, will do while/While change. Will take care in next patch.
>
> >
> >> mask instead of multiple shifting operations for each error.
> >
> >
> >>
> >> Fixes: d8703554f4de ("i2c: qcom-geni: Add support for GPI DMA")
> >> Co-developed-by: Viken Dadhaniya <quic_vdadhani@quicinc.com>
> >> Signed-off-by: Viken Dadhaniya <quic_vdadhani@quicinc.com>
> >> Signed-off-by: Mukesh Kumar Savaliya <quic_msavaliy@quicinc.com>
> >> ---
> >> ---
> Sorry, i Missed to add V1 -> V2 : will add into next patch upload.
> >> - Commit log changed we->We.
> >> - Explained the problem that we are not detecing NACK error.
> >> - Removed Heap based memory allocation and hence memory leakage issue.
> >> - Used FIELD_GET and removed shiting and masking every time as suggested by Bjorn.
> >> - Changed commit log to reflect the code changes done.
> >> - Removed adding anything into struct gpi_i2c_config and created new structure
> >>    for error status as suggested by Bjorn.
> >> ---
> >>   drivers/dma/qcom/gpi.c             | 12 +++++++++++-
> >>   drivers/i2c/busses/i2c-qcom-geni.c | 19 +++++++++++++++----
> >>   include/linux/dma/qcom-gpi-dma.h   | 10 ++++++++++
> >>   3 files changed, 36 insertions(+), 5 deletions(-)
> >>
> >> diff --git a/drivers/dma/qcom/gpi.c b/drivers/dma/qcom/gpi.c
> >> index 1c93864e0e4d..e3508d51fdc9 100644
> >> --- a/drivers/dma/qcom/gpi.c
> >> +++ b/drivers/dma/qcom/gpi.c
> >> @@ -1076,7 +1076,17 @@ static void gpi_process_xfer_compl_event(struct gchan *gchan,
> >>          dev_dbg(gpii->gpi_dev->dev, "Residue %d\n", result.residue);
> >>
> >>          dma_cookie_complete(&vd->tx);
> >> -       dmaengine_desc_get_callback_invoke(&vd->tx, &result);
> >> +       if (gchan->protocol == QCOM_GPI_I2C) {
> >> +               struct dmaengine_desc_callback cb;
> >> +               struct gpi_i2c_result *i2c;
> >> +
> >> +               dmaengine_desc_get_callback(&vd->tx, &cb);
> >> +               i2c = cb.callback_param;
> >> +               i2c->status = compl_event->status;
> >> +               dmaengine_desc_callback_invoke(&cb, &result);
> >> +       } else {
> >> +               dmaengine_desc_get_callback_invoke(&vd->tx, &result);
> >
> > Is there such error reporting for SPI or UART protocols?
> >
>
> Such errors are not there for SPI or UART because
> NACK/BUS_PROTO/ARB_LOST errors are protocol specific errors. These error
> comes in
> middle of the transfers. As these are like expected protocol errors
> depending on the slave device/s response.

Yes, these particular errors are I2C specific. My question was more
generic: do we have any similar errors for SPI or UART GENI protocols
that we should report from GPI to the corresponding driver?

>
> >> +       }
> >>
> >>   gpi_free_desc:
> >>          spin_lock_irqsave(&gchan->vc.lock, flags);
> >> diff --git a/drivers/i2c/busses/i2c-qcom-geni.c b/drivers/i2c/busses/i2c-qcom-geni.c
> >> index da94df466e83..36a7c0c0ff54 100644
> >> --- a/drivers/i2c/busses/i2c-qcom-geni.c
> >> +++ b/drivers/i2c/busses/i2c-qcom-geni.c
> >> @@ -66,6 +66,7 @@ enum geni_i2c_err_code {
> >>          GENI_TIMEOUT,
> >>   };
> >>
> >> +#define I2C_DMA_TX_IRQ_MASK    GENMASK(12, 5)
> >>   #define DM_I2C_CB_ERR          ((BIT(NACK) | BIT(BUS_PROTO) | BIT(ARB_LOST)) \
> >>                                                                          << 5)
> >>
> >> @@ -99,6 +100,7 @@ struct geni_i2c_dev {
> >>          struct dma_chan *rx_c;
> >>          bool gpi_mode;
> >>          bool abort_done;
> >> +       struct gpi_i2c_result i2c_result;
> >>   };
> >>
> >>   struct geni_i2c_desc {
> >> @@ -484,9 +486,18 @@ static int geni_i2c_tx_one_msg(struct geni_i2c_dev *gi2c, struct i2c_msg *msg,
> >>
> >>   static void i2c_gpi_cb_result(void *cb, const struct dmaengine_result *result)
> >>   {
> >> -       struct geni_i2c_dev *gi2c = cb;
> >> -
> >> -       if (result->result != DMA_TRANS_NOERROR) {
> >> +       struct gpi_i2c_result *i2c_res = cb;
> >> +       struct geni_i2c_dev *gi2c = container_of(i2c_res, struct geni_i2c_dev, i2c_result);
> >> +       u32 status;
> >> +
> >> +       status = FIELD_GET(I2C_DMA_TX_IRQ_MASK, i2c_res->status);
> >> +       if (status == BIT(NACK)) {
> >> +               geni_i2c_err(gi2c, NACK);
> >> +       } else if (status == BIT(BUS_PROTO)) {
> >> +               geni_i2c_err(gi2c, BUS_PROTO);
> >> +       } else if (status == BIT(ARB_LOST)) {
> >> +               geni_i2c_err(gi2c, ARB_LOST);
> >> +       } else if (result->result != DMA_TRANS_NOERROR) {
> >>                  dev_err(gi2c->se.dev, "DMA txn failed:%d\n", result->result);
> >>                  gi2c->err = -EIO;
> >>          } else if (result->residue) {
> >> @@ -568,7 +579,7 @@ static int geni_i2c_gpi(struct geni_i2c_dev *gi2c, struct i2c_msg *msg,
> >>          }
> >>
> >>          desc->callback_result = i2c_gpi_cb_result;
> >> -       desc->callback_param = gi2c;
> >> +       desc->callback_param = &gi2c->i2c_result;
> >>
> >>          dmaengine_submit(desc);
> >>          *buf = dma_buf;
> >> diff --git a/include/linux/dma/qcom-gpi-dma.h b/include/linux/dma/qcom-gpi-dma.h
> >> index 6680dd1a43c6..f585c6a35e51 100644
> >> --- a/include/linux/dma/qcom-gpi-dma.h
> >> +++ b/include/linux/dma/qcom-gpi-dma.h
> >> @@ -80,4 +80,14 @@ struct gpi_i2c_config {
> >>          bool multi_msg;
> >>   };
> >>
> >> +/**
> >> + * struct gpi_i2c_result - i2c transfer status result in GSI mode
> >> + *
> >> + * @status: store txfer status value as part of callback
> >> + *
> >> + */
> >> +struct gpi_i2c_result {
> >> +       u32 status;
> >> +};
> >> +
> >>   #endif /* QCOM_GPI_DMA_H */
> >> --
> >> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> >> a Linux Foundation Collaborative Project
> >>
> >>
> >
> >


-- 
With best wishes
Dmitry