Re: [PATCH] mmc: meson-gx: Convert host->lock to raw spinlock

[Sean Anderson <sanderson@brivo.com>]

On 9/28/26 12:17 PM, Ulf Hansson wrote:
> On Mon, Sep 21, 2026 at 9:14 PM Sean Anderson <sanderson@brivo.com> wrote:
>>
>> The primary handler for IRQF_ONESHOT interrupts is always run without
>> threading, even on PREEMPT_RT. Therefore, we must use a raw spinlock,
>> which will never sleep (even on PREEMPT_RT).
> 
> Sorry, but I don't quite understand the above. Are you saying that
> IRQF_ONESHOT only works with raw spinlocks?

The primary handler of an IRQF_ONESHOT handler must use raw spinlocks.

https://www.kernel.org/doc/html/latest/core-api/real-time/differences.html#interrupt-handling

> 
>>
>> Fixes: 066ecde6d826 ("mmc: meson-gx: add SDIO interrupt support")
>> Signed-off-by: Sean Anderson <sanderson@brivo.com>
>> ---
>>
>>   drivers/mmc/host/meson-gx-mmc.c | 12 ++++++------
>>   1 file changed, 6 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/mmc/host/meson-gx-mmc.c b/drivers/mmc/host/meson-gx-mmc.c
>> index 694bb443d5f3f..d5365c0404cb9 100644
>> --- a/drivers/mmc/host/meson-gx-mmc.c
>> +++ b/drivers/mmc/host/meson-gx-mmc.c
>> @@ -176,7 +176,7 @@ struct meson_host {
>>
>>          bool needs_pre_post_req;
>>
>> -       spinlock_t lock;
>> +       raw_spinlock_t lock;
>>   };
>>
>>   #define CMD_CFG_LENGTH_MASK GENMASK(8, 0)
>> @@ -953,10 +953,10 @@ static irqreturn_t meson_mmc_irq(int irq, void *dev_id)
>>          cmd = host->cmd;
>>
>>          if (status & IRQ_SDIO) {
>> -               spin_lock(&host->lock);
>> +               raw_spin_lock(&host->lock);
>>                  __meson_mmc_enable_sdio_irq(host->mmc, 0);
>>                  sdio_signal_irq(host->mmc);
>> -               spin_unlock(&host->lock);
>> +               raw_spin_unlock(&host->lock);
>>                  status &= ~IRQ_SDIO;
>>                  if (!status)
>>                          return IRQ_HANDLED;
>> @@ -1112,9 +1112,9 @@ static void meson_mmc_enable_sdio_irq(struct mmc_host *mmc, int enable)
>>          struct meson_host *host = mmc_priv(mmc);
>>          unsigned long flags;
>>
>> -       spin_lock_irqsave(&host->lock, flags);
>> +       raw_spin_lock_irqsave(&host->lock, flags);
>>          __meson_mmc_enable_sdio_irq(mmc, enable);
>> -       spin_unlock_irqrestore(&host->lock, flags);
>> +       raw_spin_unlock_irqrestore(&host->lock, flags);
>>   }
>>
>>   static void meson_mmc_ack_sdio_irq(struct mmc_host *mmc)
>> @@ -1225,7 +1225,7 @@ static int meson_mmc_probe(struct platform_device *pdev)
>>          if (ret)
>>                  goto err_init_clk;
>>
>> -       spin_lock_init(&host->lock);
>> +       raw_spin_lock_init(&host->lock);
>>
>>          if (host->dram_access_quirk) {
>>                  /* Limit segments to 1 due to low available sram memory */
>> ---
>> base-commit: 587858367581b9c55c3690f4e63382ad622719d4
>> branch: meson_mmc_raw
>>
>> --
>> 2.53.0
>>