Re: [PATCH v3 2/2] spi: qcom-geni: Add panic notifier to cancel and reset DMA during panic

[Praveen Talari <praveen.talari@oss.qualcomm.com>]

Hi Jyothi,

Thank you for review.

On 21-08-2026 16:19, Jyothi Kumar Seerapu wrote:
>
>
> On 8/18/2026 6:58 PM, Praveen Talari wrote:
>> When a VM crashes with an active SPI DMA transfer in progress, the
>> SMMU raises context faults as the DMA engine continues to access
>> IOVAs that are invalidated when the VM's memory context is torn down.
>> These faults can affect other VMs sharing the same SMMU instance and
>> obscure the root cause of the crash.
>>
>> Register a panic notifier that cancels (or aborts, if cancel doesn't
>> complete) the in-flight command and resets the TX/RX DMA FSMs, so the
>> DMA engine stops issuing transactions against invalidated IOVAs
>> before the system halts. For GPI DMA mode, the DMA channels are
>> terminated directly via dmaengine_terminate_async().
>>
>> The notifier bails out early if the device is not runtime-active or
>> if there's no active GENI command, avoiding unnecessary register
>> accesses while the SE is clock-gated or idle.
>>
>> Since panic notifiers run with IRQs and preemption disabled,
>> completion-based waits used by the regular error-handling path
>> (handle_se_timeout()) cannot be reused here. Instead, the relevant
>> status registers are polled directly with
>> readl_poll_timeout_atomic(), which is safe to call in this context.
>>
>> Signed-off-by: Praveen Talari <praveen.talari@oss.qualcomm.com>
>> ---
>>   drivers/spi/spi-geni-qcom.c | 68 
>> +++++++++++++++++++++++++++++++++++++++++++++
>>   1 file changed, 68 insertions(+)
>>
>> diff --git a/drivers/spi/spi-geni-qcom.c b/drivers/spi/spi-geni-qcom.c
>> index c65c1788325d..f272bd0cb640 100644
>> --- a/drivers/spi/spi-geni-qcom.c
>> +++ b/drivers/spi/spi-geni-qcom.c
>> @@ -12,8 +12,10 @@
>>   #include <linux/dma/qcom-gpi-dma.h>
>>   #include <linux/interrupt.h>
>>   #include <linux/io.h>
>> +#include <linux/iopoll.h>
>>   #include <linux/log2.h>
>>   #include <linux/module.h>
>> +#include <linux/panic_notifier.h>
>>   #include <linux/platform_device.h>
>>   #include <linux/pm_opp.h>
>>   #include <linux/pm_runtime.h>
>> @@ -115,6 +117,7 @@ struct spi_geni_master {
>>       struct dma_chan *rx;
>>       int cur_xfer_mode;
>>       const struct geni_spi_desc *dev_data;
>> +    struct notifier_block panic_nb;
>>   };
>>     static void spi_slv_setup(struct spi_geni_master *mas)
>> @@ -1073,6 +1076,62 @@ static void spi_geni_shutdown(struct 
>> platform_device *pdev)
>>       spi_controller_suspend(spi);
>>   }
>>   +static int spi_geni_panic_notifier(struct notifier_block *nb,
>> +                   unsigned long action, void *data)
>> +{
>> +    struct spi_geni_master *mas = container_of(nb, struct 
>> spi_geni_master, panic_nb);
>> +    struct spi_controller *spi = dev_get_drvdata(mas->dev);
>> +    struct geni_se *se = &mas->se;
>> +    u32 val;
>> +
>> +    if (!pm_runtime_active(mas->dev))
>> +        return NOTIFY_OK;
>> +
>> +    if (mas->cur_xfer_mode == GENI_GPI_DMA) {
>> +        dmaengine_terminate_async(mas->tx);
>> +        dmaengine_terminate_async(mas->rx);
>> +        return NOTIFY_OK;
>> +    }
>> +
>> +    if (!(readl_relaxed(se->base + SE_GENI_STATUS) & 
>> M_GENI_CMD_ACTIVE))
>> +        return NOTIFY_OK;
>> +
>> +    if (!spi->target) {
>> +        geni_se_cancel_m_cmd(se);
>> +        if (!readl_poll_timeout_atomic(se->base + 
>> SE_GENI_M_IRQ_STATUS, val,
>> +                           val & M_CMD_CANCEL_EN, 10, 50000)) {
>> +            writel_relaxed(M_CMD_CANCEL_EN, se->base + 
>> SE_GENI_M_IRQ_CLEAR);
>> +            return NOTIFY_OK;
> Looks like a successful cancel here returns NOTIFY_OK directly, 
> skipping the FSM reset block below it entirely. Is that the correct 
> expectation ?> +        }

If the cancel operation succeeds, an FSM reset is not required. If it 
fails, the driver proceeds with an abort sequence followed by an FSM reset.


Thanks,

Praveen Talari

>> +    }
>> +
>> +    geni_se_abort_m_cmd(se);
>> +    if (!readl_poll_timeout_atomic(se->base + SE_GENI_M_IRQ_STATUS, 
>> val,
>> +                       val & M_CMD_ABORT_EN, 10, 50000))
>> +        writel_relaxed(M_CMD_ABORT_EN, se->base + SE_GENI_M_IRQ_CLEAR);
>> +
>> +    if (mas->cur_xfer_mode == GENI_SE_DMA) {
>> +        writel_relaxed(1, se->base + SE_DMA_TX_FSM_RST);
>> +        readl_poll_timeout_atomic(se->base + SE_DMA_TX_IRQ_STAT, val,
>> +                      val & TX_RESET_DONE, 10, 50000);
>> +        writel_relaxed(val, se->base + SE_DMA_TX_IRQ_CLR);
>> +
>> +        writel_relaxed(1, se->base + SE_DMA_RX_FSM_RST);
>> +        readl_poll_timeout_atomic(se->base + SE_DMA_RX_IRQ_STAT, val,
>> +                      val & RX_RESET_DONE, 10, 50000);
>> +        writel_relaxed(val, se->base + SE_DMA_RX_IRQ_CLR);
>> +    }
>> +
>> +    return NOTIFY_OK;
>> +}
>> +
>> +static void spi_geni_unregister_notifiers(void *data)
>> +{
>> +    struct spi_geni_master *mas = data;
>> +
>> +    atomic_notifier_chain_unregister(&panic_notifier_list, 
>> &mas->panic_nb);
>> +}
>> +
>>   static int spi_geni_probe(struct platform_device *pdev)
>>   {
>>       int ret, irq;
>> @@ -1161,6 +1220,15 @@ static int spi_geni_probe(struct 
>> platform_device *pdev)
>>       if (ret)
>>           return ret;
>>   +    mas->panic_nb.notifier_call = spi_geni_panic_notifier;
>> +    ret = atomic_notifier_chain_register(&panic_notifier_list, 
>> &mas->panic_nb);
>> +    if (ret)
>> +        return ret;
>> +
>> +    ret = devm_add_action_or_reset(dev, 
>> spi_geni_unregister_notifiers, mas);
>> +    if (ret)
>> +        return ret;
>> +
>>       return devm_spi_register_controller(dev, spi);
>>   }
>>
>