From: Akash Asthana <akashast@codeaurora.org>
To: Roja Rani Yarubandi <rojay@codeaurora.org>, wsa@kernel.org
Cc: swboyd@chromium.org, dianders@chromium.org,
saiprakash.ranjan@codeaurora.org, gregkh@linuxfoundation.org,
mka@chromium.org, msavaliy@qti.qualcomm.com,
skakit@codeaurora.org, rnayak@codeaurora.org, agross@kernel.org,
bjorn.andersson@linaro.org, linux-arm-msm@vger.kernel.org,
linux-i2c@vger.kernel.org, linux-kernel@vger.kernel.org,
sumit.semwal@linaro.org, linux-media@vger.kernel.org,
dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org
Subject: Re: [PATCH V2 2/2] i2c: i2c-qcom-geni: Add shutdown callback for i2c
Date: Wed, 26 Aug 2020 17:26:30 +0530 [thread overview]
Message-ID: <ba1935d2-9fec-cf82-ed19-bc005befcb40@codeaurora.org> (raw)
In-Reply-To: <20200820103522.26242-3-rojay@codeaurora.org>
Hi Roja,
On 8/20/2020 4:05 PM, Roja Rani Yarubandi wrote:
> If the hardware is still accessing memory after SMMU translation
> is disabled (as part of smmu shutdown callback), then the
> IOVAs (I/O virtual address) which it was using will go on the bus
> as the physical addresses which will result in unknown crashes
> like NoC/interconnect errors.
>
> So, implement shutdown callback to i2c driver to unmap DMA mappings
> during system "reboot" or "shutdown".
>
> Signed-off-by: Roja Rani Yarubandi <rojay@codeaurora.org>
> ---
> Changes in V2:
> - As per Stephen's comments added seperate function for stop transfer,
> fixed minor nitpicks.
>
> drivers/i2c/busses/i2c-qcom-geni.c | 43 ++++++++++++++++++++++++++++++
> include/linux/qcom-geni-se.h | 5 ++++
> 2 files changed, 48 insertions(+)
>
> diff --git a/drivers/i2c/busses/i2c-qcom-geni.c b/drivers/i2c/busses/i2c-qcom-geni.c
> index 1fda5c7c2cfc..d07f2f33bb75 100644
> --- a/drivers/i2c/busses/i2c-qcom-geni.c
> +++ b/drivers/i2c/busses/i2c-qcom-geni.c
> @@ -486,6 +486,28 @@ static int geni_i2c_xfer(struct i2c_adapter *adap,
> return ret;
> }
>
> +static void geni_i2c_stop_xfer(struct geni_i2c_dev *gi2c)
> +{
> + u32 val;
> + struct geni_se *se = &gi2c->se;
> +
> + val = readl_relaxed(gi2c->se.base + SE_DMA_DEBUG_REG0);
> + if (val & DMA_TX_ACTIVE) {
> + geni_i2c_abort_xfer(gi2c);
> + gi2c->cur_wr = 0;
> + if (gi2c->err)
> + geni_i2c_tx_fsm_rst(gi2c);
> + geni_se_tx_dma_unprep(se, gi2c->tx_dma, gi2c->xfer_len);
> + }
should be 'else if', because TX and RX can't happen parallel.
> + if (val & DMA_RX_ACTIVE) {
> + geni_i2c_abort_xfer(gi2c);
> + gi2c->cur_rd = 0;
> + if (gi2c->err)
> + geni_i2c_rx_fsm_rst(gi2c);
> + geni_se_rx_dma_unprep(se, gi2c->rx_dma, gi2c->xfer_len);
> + }
> +}
> +
> static u32 geni_i2c_func(struct i2c_adapter *adap)
> {
> return I2C_FUNC_I2C | (I2C_FUNC_SMBUS_EMUL & ~I2C_FUNC_SMBUS_QUICK);
> @@ -617,6 +639,26 @@ static int geni_i2c_remove(struct platform_device *pdev)
> return 0;
> }
>
> +static void geni_i2c_shutdown(struct platform_device *pdev)
> +{
> + int ret;
> + u32 dma;
> + struct geni_i2c_dev *gi2c = platform_get_drvdata(pdev);
> + struct geni_se *se = &gi2c->se;
> +
> + ret = pm_runtime_get_sync(gi2c->se.dev);
> + if (ret < 0) {
> + dev_err(gi2c->se.dev, "Failed to resume device: %d\n", ret);
> + return;
> + }
> +
> + dma = readl_relaxed(se->base + SE_GENI_DMA_MODE_EN);
Wrt to current issue context it may be suffice to stop just DMA mode
transfers but why not stop all mode of active transfer during shutdown
in a generic way.
Regards,
Akash
> + if (dma)
> + geni_i2c_stop_xfer(gi2c);
> +
> + pm_runtime_put_sync_suspend(gi2c->se.dev);
> +}
> +
> static int __maybe_unused geni_i2c_runtime_suspend(struct device *dev)
> {
> int ret;
> @@ -677,6 +719,7 @@ MODULE_DEVICE_TABLE(of, geni_i2c_dt_match);
> static struct platform_driver geni_i2c_driver = {
> .probe = geni_i2c_probe,
> .remove = geni_i2c_remove,
> + .shutdown = geni_i2c_shutdown,
> .driver = {
> .name = "geni_i2c",
> .pm = &geni_i2c_pm_ops,
> diff --git a/include/linux/qcom-geni-se.h b/include/linux/qcom-geni-se.h
> index dd464943f717..c3c016496d98 100644
> --- a/include/linux/qcom-geni-se.h
> +++ b/include/linux/qcom-geni-se.h
> @@ -77,6 +77,7 @@ struct geni_se {
> #define SE_DMA_RX_FSM_RST 0xd58
> #define SE_HW_PARAM_0 0xe24
> #define SE_HW_PARAM_1 0xe28
> +#define SE_DMA_DEBUG_REG0 0xe40
>
> /* GENI_FORCE_DEFAULT_REG fields */
> #define FORCE_DEFAULT BIT(0)
> @@ -207,6 +208,10 @@ struct geni_se {
> #define RX_GENI_CANCEL_IRQ BIT(11)
> #define RX_GENI_GP_IRQ_EXT GENMASK(13, 12)
>
> +/* SE_DMA_DEBUG_REG0 Register fields */
> +#define DMA_TX_ACTIVE BIT(0)
> +#define DMA_RX_ACTIVE BIT(1)
> +
> /* SE_HW_PARAM_0 fields */
> #define TX_FIFO_WIDTH_MSK GENMASK(29, 24)
> #define TX_FIFO_WIDTH_SHFT 24
--
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,\na Linux Foundation Collaborative Project
next prev parent reply other threads:[~2020-08-26 11:57 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-20 10:35 [PATCH V2 0/2] Implement Shutdown callback for i2c Roja Rani Yarubandi
2020-08-20 10:35 ` [PATCH V2 1/2] i2c: i2c-qcom-geni: Store DMA mapping data in geni_i2c_dev struct Roja Rani Yarubandi
2020-08-21 0:18 ` Stephen Boyd
2020-08-28 11:45 ` rojay
2020-08-26 11:55 ` Akash Asthana
2020-09-07 12:51 ` rojay
2020-08-20 10:35 ` [PATCH V2 2/2] i2c: i2c-qcom-geni: Add shutdown callback for i2c Roja Rani Yarubandi
2020-08-21 0:22 ` Stephen Boyd
2020-08-28 11:46 ` rojay
2020-08-26 11:56 ` Akash Asthana [this message]
2020-09-07 12:53 ` rojay
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