linux-kernel - Re: [PATCH V5 3/3] i2c: i2c-qcom-geni: Add shutdown callback for i2c

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Message-ID: <160168919332.310579.15311671258384969025@swboyd.mtv.corp.google.com>
Date:   Fri, 02 Oct 2020 18:39:53 -0700
From:   Stephen Boyd <swboyd@...omium.org>
To:     Roja Rani Yarubandi <rojay@...eaurora.org>, wsa@...nel.org
Cc:     dianders@...omium.org, saiprakash.ranjan@...eaurora.org,
        gregkh@...uxfoundation.org, mka@...omium.org,
        akashast@...eaurora.org, msavaliy@....qualcomm.com,
        skakit@...eaurora.org, vkaur@...eaurora.org,
        pyarlaga@...eaurora.org, rnayak@...eaurora.org, agross@...nel.org,
        bjorn.andersson@...aro.org, linux-arm-msm@...r.kernel.org,
        linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org,
        sumit.semwal@...aro.org, linux-media@...r.kernel.org,
        Roja Rani Yarubandi <rojay@...eaurora.org>
Subject: Re: [PATCH V5 3/3] i2c: i2c-qcom-geni: Add shutdown callback for i2c

Quoting Roja Rani Yarubandi (2020-10-01 01:44:25)
> diff --git a/drivers/i2c/busses/i2c-qcom-geni.c b/drivers/i2c/busses/i2c-qcom-geni.c
> index aee2a1dd2c62..56d3fbfe7eb6 100644
> --- a/drivers/i2c/busses/i2c-qcom-geni.c
> +++ b/drivers/i2c/busses/i2c-qcom-geni.c
> @@ -380,6 +380,36 @@ static void geni_i2c_tx_msg_cleanup(struct geni_i2c_dev *gi2c,
>         }
>  }
>  
> +static void geni_i2c_stop_xfer(struct geni_i2c_dev *gi2c)
> +{
> +       int ret;
> +       u32 geni_status;
> +       unsigned long flags;
> +       struct i2c_msg *cur;
> +
> +       /* Resume device, runtime suspend can happen anytime during transfer */
> +       ret = pm_runtime_get_sync(gi2c->se.dev);
> +       if (ret < 0) {
> +               dev_err(gi2c->se.dev, "Failed to resume device: %d\n", ret);
> +               return;
> +       }
> +
> +       spin_lock_irqsave(&gi2c->lock, flags);

We grab the lock here.

> +       geni_status = readl_relaxed(gi2c->se.base + SE_GENI_STATUS);
> +       if (!(geni_status & M_GENI_CMD_ACTIVE))
> +               goto out;
> +
> +       cur = gi2c->cur;
> +       geni_i2c_abort_xfer(gi2c);

But it looks like this function takes the lock again? Did you test this
with lockdep enabled? It should hang even without lockdep, so it seems
like this path of code has not been tested.

> +       if (cur->flags & I2C_M_RD)
> +               geni_i2c_rx_msg_cleanup(gi2c, cur);
> +       else
> +               geni_i2c_tx_msg_cleanup(gi2c, cur);
> +       spin_unlock_irqrestore(&gi2c->lock, flags);
> +out:
> +       pm_runtime_put_sync_suspend(gi2c->se.dev);
> +}
> +
>  static int geni_i2c_rx_one_msg(struct geni_i2c_dev *gi2c, struct i2c_msg *msg,
>                                 u32 m_param)
>  {