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SubjectRe: [PATCH V2 2/2] i2c: i2c-qcom-geni: Add shutdown callback for i2c
On 2020-08-21 05:52, Stephen Boyd wrote:
> Quoting Roja Rani Yarubandi (2020-08-20 03:35:22)
>> 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>
>> ---
>
> I'd still put a Fixes tag because it's fixing the driver when someone
> runs shutdown.
>

Okay, will add fixes tag.

>> 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);
>> + }
>> + 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);
>> + if (dma)
>> + geni_i2c_stop_xfer(gi2c);
>
> Any reason the if (dma) check isn't inside geni_i2c_stop_xfer()?
> Checking for dma and then bailing out early should work and keep the
> logic in one function. Then the pm_runtime_sync() call could go in
> there
> too and if (!dma) goto out. This assumes that we're going to call
> geni_i2c_stop_xfer() from somewhere else, like if a transfer times out
> or something?
>

Okay, will do the changes.

>> +
>> + pm_runtime_put_sync_suspend(gi2c->se.dev);
>> +}
>> +
>> static int __maybe_unused geni_i2c_runtime_suspend(struct device
>> *dev)
>> {
>> int ret;

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