Re: [PATCH 2/5] mmc: tmio: Provide separate interrupt handlers

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On Tue, 16 Aug 2011, Simon Horman wrote:

> Provide separate interrupt handlers which may be used by platforms where
> SDHI has three interrupt sources.

Yes, this looks much simpler and cleaner to me now, than 3 original 
patches. It might change a bit after you change your PATCH 1/5, 

> 
> This involves two key changes to the logic:
> 1. Do not assume that only one interrupt has occurred.
>    In particular because tmio_mmc_irq() handles interrupts
>    from three sources. Also, because this allows
>    the logic to be simplified.
> 2. Just ignore spurious interrupts.
>    Its not clear to me that they can ever occur.
> 
> This patch also removes the commented-out handling of CRC and other errors.
> 
> Cc: Guennadi Liakhovetski <g.liakhovetski@xxxxxx>
> Cc: Magnus Damm <magnus.damm@xxxxxxxxx>
> Signed-off-by: Simon Horman <horms@xxxxxxxxxxxx>
> 
> ---
> 
> * SDCARD portion tested on AP4/Mackerel
> * SDIO portion untested
> 
> v2
> As suggested by Guennadi Liakhovetski
> * Combine 3 patches into one
> * Reduce the number of __tmio_..._irq() functions
> * Rename "...card_access..." functions as "...sdcard..."
> ---
>  drivers/mmc/host/tmio_mmc.h     |    3 +
>  drivers/mmc/host/tmio_mmc_pio.c |  121 +++++++++++++++++++++++----------------
>  2 files changed, 75 insertions(+), 49 deletions(-)
> 
> diff --git a/drivers/mmc/host/tmio_mmc.h b/drivers/mmc/host/tmio_mmc.h
> index 1cf8db5..3020f98 100644
> --- a/drivers/mmc/host/tmio_mmc.h
> +++ b/drivers/mmc/host/tmio_mmc.h
> @@ -97,6 +97,9 @@ void tmio_mmc_do_data_irq(struct tmio_mmc_host *host);
>  void tmio_mmc_enable_mmc_irqs(struct tmio_mmc_host *host, u32 i);
>  void tmio_mmc_disable_mmc_irqs(struct tmio_mmc_host *host, u32 i);
>  irqreturn_t tmio_mmc_irq(int irq, void *devid);
> +irqreturn_t tmio_mmc_sdcard_irq(int irq, void *devid);
> +irqreturn_t tmio_mmc_card_detect_irq(int irq, void *devid);
> +irqreturn_t tmio_mmc_sdio_irq(int irq, void *devid);
>  
>  static inline char *tmio_mmc_kmap_atomic(struct scatterlist *sg,
>  					 unsigned long *flags)
> diff --git a/drivers/mmc/host/tmio_mmc_pio.c b/drivers/mmc/host/tmio_mmc_pio.c
> index c60b15f..e9640f2 100644
> --- a/drivers/mmc/host/tmio_mmc_pio.c
> +++ b/drivers/mmc/host/tmio_mmc_pio.c
> @@ -547,45 +547,20 @@ out:
>  	spin_unlock(&host->lock);
>  }
>  
> -irqreturn_t tmio_mmc_irq(int irq, void *devid)
> +static void tmio_mmc_card_irq_status(struct tmio_mmc_host *host,
> +				       int *ireg, int *status)
>  {
> -	struct tmio_mmc_host *host = devid;
> -	struct mmc_host *mmc = host->mmc;
> -	struct tmio_mmc_data *pdata = host->pdata;
> -	unsigned int ireg, status;
> -	unsigned int sdio_ireg, sdio_status;
> -
> -	pr_debug("MMC IRQ begin\n");
> -
> -	status = sd_ctrl_read32(host, CTL_STATUS);
> -	ireg = status & TMIO_MASK_IRQ & ~host->sdcard_irq_mask;
> +	*status = sd_ctrl_read32(host, CTL_STATUS);
> +	*ireg = *status & TMIO_MASK_IRQ & ~host->sdcard_irq_mask;
>  
> -	sdio_ireg = 0;
> -	if (!ireg && pdata->flags & TMIO_MMC_SDIO_IRQ) {
> -		sdio_status = sd_ctrl_read16(host, CTL_SDIO_STATUS);
> -		host->sdio_irq_mask = sd_ctrl_read16(host, CTL_SDIO_IRQ_MASK);
> -		sdio_ireg = sdio_status & TMIO_SDIO_MASK_ALL &
> -				~host->sdio_irq_mask;
> -
> -		sd_ctrl_write16(host, CTL_SDIO_STATUS, sdio_status & ~TMIO_SDIO_MASK_ALL);
> -
> -		if (sdio_ireg && !host->sdio_irq_enabled) {
> -			pr_warning("tmio_mmc: Spurious SDIO IRQ, disabling! 0x%04x 0x%04x 0x%04x\n",
> -				   sdio_status, host->sdio_irq_mask, sdio_ireg);
> -			tmio_mmc_enable_sdio_irq(mmc, 0);
> -			goto out;
> -		}
> -
> -		if (mmc->caps & MMC_CAP_SDIO_IRQ &&
> -			sdio_ireg & TMIO_SDIO_STAT_IOIRQ)
> -			mmc_signal_sdio_irq(mmc);
> -
> -		if (sdio_ireg)
> -			goto out;
> -	}
> +	pr_debug_status(*status);
> +	pr_debug_status(*ireg);
> +}
>  
> -	pr_debug_status(status);
> -	pr_debug_status(ireg);
> +static void __tmio_mmc_card_detect_irq(struct tmio_mmc_host *host,
> +				       int ireg, int status)
> +{
> +	struct mmc_host *mmc = host->mmc;
>  
>  	/* Card insert / remove attempts */
>  	if (ireg & (TMIO_STAT_CARD_INSERT | TMIO_STAT_CARD_REMOVE)) {
> @@ -595,43 +570,91 @@ irqreturn_t tmio_mmc_irq(int irq, void *devid)
>  		     ((ireg & TMIO_STAT_CARD_INSERT) && !mmc->card)) &&
>  		    !work_pending(&mmc->detect.work))
>  			mmc_detect_change(host->mmc, msecs_to_jiffies(100));
> -		goto out;
>  	}
> +}
>  
> -	/* CRC and other errors */
> -/*	if (ireg & TMIO_STAT_ERR_IRQ)
> - *		handled |= tmio_error_irq(host, irq, stat);
> - */
> +irqreturn_t tmio_mmc_card_detect_irq(int irq, void *devid)
> +{
> +	unsigned int ireg, status;
> +	struct tmio_mmc_host *host = devid;
> +
> +	tmio_mmc_card_irq_status(host, &ireg, &status);
> +	__tmio_mmc_card_detect_irq(host, ireg, status);
>  
> +	return IRQ_HANDLED;
> +}
> +EXPORT_SYMBOL(tmio_mmc_card_detect_irq);
> +
> +void __tmio_mmc_sdcard_irq(struct tmio_mmc_host *host, int ireg, int status)

"static" missing

> +{
>  	/* Command completion */
>  	if (ireg & (TMIO_STAT_CMDRESPEND | TMIO_STAT_CMDTIMEOUT)) {
>  		tmio_mmc_ack_mmc_irqs(host,
>  			     TMIO_STAT_CMDRESPEND |
>  			     TMIO_STAT_CMDTIMEOUT);
>  		tmio_mmc_cmd_irq(host, status);
> -		goto out;

Well, removing these goto's certainly changes behaviour - at least 
theoretically. Imagine entering the ISR with status = TMIO_STAT_CMDRESPEND 
| TMIO_STAT_DATAEND. Before your patch the driver would ack and process 
the TMIO_STAT_CMDRESPEND and return dropping the TMIO_STAT_DATAEND status. 
Anc we don't know whether a second interrupt would follow with 
TMIO_STAT_DATAEND set. After your patch the driver will ack and process 
both. Since this driver runs on a variaty of hardware, unless fixing a 
problem or really improving something, I would keep the original 
behaviour. So, I would rather keep those exit points - just put "return" 
there.

>  	}
>  
>  	/* Data transfer */
>  	if (ireg & (TMIO_STAT_RXRDY | TMIO_STAT_TXRQ)) {
>  		tmio_mmc_ack_mmc_irqs(host, TMIO_STAT_RXRDY | TMIO_STAT_TXRQ);
>  		tmio_mmc_pio_irq(host);
> -		goto out;
>  	}
>  
>  	/* Data transfer completion */
>  	if (ireg & TMIO_STAT_DATAEND) {
>  		tmio_mmc_ack_mmc_irqs(host, TMIO_STAT_DATAEND);
>  		tmio_mmc_data_irq(host);
> -		goto out;
>  	}
> +}
> +
> +irqreturn_t tmio_mmc_sdcard_irq(int irq, void *devid)
> +{
> +	unsigned int ireg, status;
> +	struct tmio_mmc_host *host = devid;
>  
> -	pr_warning("tmio_mmc: Spurious irq, disabling! "
> -		"0x%08x 0x%08x 0x%08x\n", status, host->sdcard_irq_mask, ireg);
> -	pr_debug_status(status);
> -	tmio_mmc_disable_mmc_irqs(host, status & ~host->sdcard_irq_mask);
> +	tmio_mmc_card_irq_status(host, &ireg, &status);
> +	__tmio_mmc_sdcard_irq(host, ireg, status);
> +
> +	return IRQ_HANDLED;
> +}
> +EXPORT_SYMBOL(tmio_mmc_sdcard_irq);
> +
> +irqreturn_t tmio_mmc_sdio_irq(int irq, void *devid)
> +{
> +	struct tmio_mmc_host *host = devid;
> +	struct mmc_host *mmc = host->mmc;
> +	struct tmio_mmc_data *pdata = host->pdata;
> +	unsigned int ireg, status;
> +
> +	if (!(pdata->flags & TMIO_MMC_SDIO_IRQ))
> +		return IRQ_HANDLED;
> +
> +	status = sd_ctrl_read16(host, CTL_SDIO_STATUS);
> +	ireg = status & TMIO_SDIO_MASK_ALL & ~host->sdcard_irq_mask;
> +
> +	sd_ctrl_write16(host, CTL_SDIO_STATUS, status & ~TMIO_SDIO_MASK_ALL);
> +
> +	if (mmc->caps & MMC_CAP_SDIO_IRQ && ireg & TMIO_SDIO_STAT_IOIRQ)
> +		mmc_signal_sdio_irq(mmc);
> +
> +	return IRQ_HANDLED;
> +}
> +EXPORT_SYMBOL(tmio_mmc_sdio_irq);
> +
> +irqreturn_t tmio_mmc_irq(int irq, void *devid)
> +{
> +	struct tmio_mmc_host *host = devid;
> +	unsigned int ireg, status;
> +
> +	pr_debug("MMC IRQ begin\n");
> +
> +	tmio_mmc_card_irq_status(host, &ireg, &status);
> +	__tmio_mmc_card_detect_irq(host, ireg, status);

Same here - I would return, if a card hot-plug event occurred.

> +	__tmio_mmc_sdcard_irq(host, ireg, status);

Ditto

> +
> +	tmio_mmc_sdio_irq(irq, devid);

Any specific reason, why you now process SDIO IRQs last?

>  
> -out:
>  	return IRQ_HANDLED;
>  }
>  EXPORT_SYMBOL(tmio_mmc_irq);
> -- 
> 1.7.5.4

Thanks
Guennadi
---
Guennadi Liakhovetski, Ph.D.
Freelance Open-Source Software Developer
http://www.open-technology.de/
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