Re: [PATCH V2] mmc: sdhci: supporting PCI MSI

[Jackey Shen <jackey.shen@amd.com>]

On Tue, Nov 12, 2013 at 03:44:40PM +0800, Aaron Lu wrote:
> On 11/12/2013 02:56 PM, Jackey Shen wrote:
> > Enable MSI support in sdhci-pci driver and provide the mechanism
> > to fall back to Legacy Pin-based Interrupt if MSI register fails.
> > 
> > Tested with SD cards on AMD platform.
> > 
> 
> ->
> 
> > Change from V1:
> > - implement this PCI MSI feature in sdhci-pci.c instead of sdhci.c
> 
> Such words can be placed under the --- below so that it will not appear
> in git log.
> 
> > 
> > Signed-off-by: Jackey Shen <Jackey.Shen@amd.com>
> > Reviewed-by: Huang Rui <ray.huang@amd.com>
> > ---
> 
> ->
> Put change related info Here.

OK. I will update my patch.

> 
> >  drivers/mmc/host/Kconfig     | 11 +++++++++
> >  drivers/mmc/host/sdhci-pci.c | 58 ++++++++++++++++++++++++++++++++++++++++++++
> >  drivers/mmc/host/sdhci.c     | 42 ++++++++++++++++++++++++++------
> >  drivers/mmc/host/sdhci.h     |  2 ++
> >  include/linux/mmc/sdhci.h    |  2 ++
> >  5 files changed, 107 insertions(+), 8 deletions(-)
> > 
> > diff --git a/drivers/mmc/host/Kconfig b/drivers/mmc/host/Kconfig
> > index 7fc5099..a56cf27 100644
> > --- a/drivers/mmc/host/Kconfig
> > +++ b/drivers/mmc/host/Kconfig
> > @@ -68,6 +68,17 @@ config MMC_SDHCI_PCI
> >  
> >  	  If unsure, say N.
> >  
> > +config MMC_SDHCI_PCI_MSI
> > +	bool "SDHCI support with MSI on PCI bus"
> > +	depends on MMC_SDHCI_PCI && PCI_MSI
> > +	help
> > +	  This enables PCI MSI (Message Signaled Interrupts) for Secure
> > +	  Digital Host Controller Interface.
> > +
> > +	  If you have a controller with this capability, say Y or M here.
> > +
> > +	  If unsure, say N.
> > +
> >  config MMC_RICOH_MMC
> >  	bool "Ricoh MMC Controller Disabler"
> >  	depends on MMC_SDHCI_PCI
> > diff --git a/drivers/mmc/host/sdhci-pci.c b/drivers/mmc/host/sdhci-pci.c
> > index 8f75381..2ca29c0 100644
> > --- a/drivers/mmc/host/sdhci-pci.c
> > +++ b/drivers/mmc/host/sdhci-pci.c
> > @@ -1143,10 +1143,68 @@ static void sdhci_pci_hw_reset(struct sdhci_host *host)
> >  		slot->hw_reset(host);
> >  }
> >  
> > +#ifdef CONFIG_MMC_SDHCI_PCI_MSI
> > +static int sdhci_pci_setup_msi(struct sdhci_host *host, irq_handler_t handler)
> > +{
> > +	int ret;
> > +	struct pci_dev *pdev = to_pci_dev(host->mmc->parent);
> > +
> > +	host->msi_enabled = false;
> > +
> > +	ret = pci_enable_msi(pdev);
> > +	if (ret) {
> > +		pr_warn("%s: Failed to allocate MSI entry\n",
> > +			mmc_hostname(host->mmc));
> > +		return ret;
> > +	}
> > +
> > +	ret = request_irq(pdev->irq, handler, 0,
> > +		mmc_hostname(host->mmc), host);
> > +	if (ret) {
> > +		pr_warn("%s: Failed to request MSI IRQ %d: %d\n",
> > +		       mmc_hostname(host->mmc), pdev->irq, ret);
> > +		pci_disable_msi(pdev);
> > +		return ret;
> > +	}
> > +
> > +	host->irq = pdev->irq;
> > +	host->msi_enabled = true;
> > +	return ret;
> > +}
> 
> What about we only call pci_enable_msi in sdhci-pci.c and then assign
> host->irq appropriately before calling sdhci_add_host, will that work?
> The only difference would be, request_irq will have SHARED flag, but I
> suppose that's not a problem.
> 
There are 2 points for this part:
1. fall back to legacy interrupt right after MSI request fails;
2. prompt user more information about where error/warning occur.

> > +
> > +static int sdhci_pci_enable_msi(struct sdhci_host *host, irq_handler_t handler)
> > +{
> > +	return sdhci_pci_setup_msi(host, handler);
> > +}
> > +
> > +static void sdhci_pci_disable_msi(struct sdhci_host *host)
> > +{
> > +	struct pci_dev *pdev = to_pci_dev(host->mmc->parent);
> > +
> > +	if (host->msi_enabled) {
> > +		pci_disable_msi(pdev);
> > +		host->msi_enabled = false;
> > +	}
> > +}
> > +
> > +#else
> > +
> > +static int sdhci_pci_enable_msi(struct sdhci_host *host, irq_handler_t handler)
> > +{
> > +	return 0;
> > +}
> > +
> > +static void sdhci_pci_disable_msi(struct sdhci_host *host)
> > +{
> > +}
> > +#endif /* CONFIG_MMC_SDHCI_PCI_MSI */
> > +
> >  static const struct sdhci_ops sdhci_pci_ops = {
> >  	.enable_dma	= sdhci_pci_enable_dma,
> >  	.platform_bus_width	= sdhci_pci_bus_width,
> >  	.hw_reset		= sdhci_pci_hw_reset,
> > +	.enable_msi		= sdhci_pci_enable_msi,
> > +	.disable_msi		= sdhci_pci_disable_msi,
> >  };
> >  
> >  /*****************************************************************************\
> > diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
> > index 6785fb1..4c2a1ac 100644
> > --- a/drivers/mmc/host/sdhci.c
> > +++ b/drivers/mmc/host/sdhci.c
> > @@ -2554,6 +2554,31 @@ void sdhci_disable_irq_wakeups(struct sdhci_host *host)
> >  }
> >  EXPORT_SYMBOL_GPL(sdhci_disable_irq_wakeups);
> >  
> > +static int sdhci_request_irq(struct sdhci_host *host)
> > +{
> > +	int ret = 0;
> > +
> > +	/* try to enable MSI */
> > +	if (host->ops->enable_msi) {
> > +		ret = host->ops->enable_msi(host, sdhci_irq);
> > +		if (ret)
> > +			pr_warn("%s: Fall back to Pin-based Interrupt: %d\n",
> > +				mmc_hostname(host->mmc), ret);
> > +	}
> > +
> > +	if (!host->msi_enabled) {
> > +		/* fall back to legacy pin-based interrupt */
> > +		ret = request_irq(host->irq, sdhci_irq, IRQF_SHARED,
> > +				mmc_hostname(host->mmc), host);
> > +		if (ret) {
> > +			pr_err("%s: Failed to request IRQ %d: %d\n",
> > +				 mmc_hostname(host->mmc), host->irq, ret);
> > +			return ret;
> > +		}
> > +	}
> > +
> > +	return ret;
> > +}
> >  int sdhci_suspend_host(struct sdhci_host *host)
> >  {
> >  	if (host->ops->platform_suspend)
> > @@ -2570,6 +2595,8 @@ int sdhci_suspend_host(struct sdhci_host *host)
> >  	if (!device_may_wakeup(mmc_dev(host->mmc))) {
> >  		sdhci_mask_irqs(host, SDHCI_INT_ALL_MASK);
> >  		free_irq(host->irq, host);
> > +		if (host->ops->disable_msi)
> > +			host->ops->disable_msi(host);
> 
> What would happen if we do not disable/enable msi in suspend/resume host?
> We have already masked all irqs with sdhci_mask_irqs anyway.
> 
We should also remove request|free_irq at the same time, right?
I will do some tests.

Thanks,
Jackey

> Thanks,
> Aaron
> 
> >  	} else {
> >  		sdhci_enable_irq_wakeups(host);
> >  		enable_irq_wake(host->irq);
> > @@ -2589,8 +2616,7 @@ int sdhci_resume_host(struct sdhci_host *host)
> >  	}
> >  
> >  	if (!device_may_wakeup(mmc_dev(host->mmc))) {
> > -		ret = request_irq(host->irq, sdhci_irq, IRQF_SHARED,
> > -				  mmc_hostname(host->mmc), host);
> > +		ret = sdhci_request_irq(host);
> >  		if (ret)
> >  			return ret;
> >  	} else {
> > @@ -3212,13 +3238,9 @@ int sdhci_add_host(struct sdhci_host *host)
> >  
> >  	sdhci_init(host, 0);
> >  
> > -	ret = request_irq(host->irq, sdhci_irq, IRQF_SHARED,
> > -		mmc_hostname(mmc), host);
> > -	if (ret) {
> > -		pr_err("%s: Failed to request IRQ %d: %d\n",
> > -		       mmc_hostname(mmc), host->irq, ret);
> > +	ret = sdhci_request_irq(host);
> > +	if (ret)
> >  		goto untasklet;
> > -	}
> >  
> >  #ifdef CONFIG_MMC_DEBUG
> >  	sdhci_dumpregs(host);
> > @@ -3258,6 +3280,8 @@ reset:
> >  	sdhci_reset(host, SDHCI_RESET_ALL);
> >  	sdhci_mask_irqs(host, SDHCI_INT_ALL_MASK);
> >  	free_irq(host->irq, host);
> > +	if (host->ops->disable_msi)
> > +		host->ops->disable_msi(host);
> >  #endif
> >  untasklet:
> >  	tasklet_kill(&host->card_tasklet);
> > @@ -3301,6 +3325,8 @@ void sdhci_remove_host(struct sdhci_host *host, int dead)
> >  
> >  	sdhci_mask_irqs(host, SDHCI_INT_ALL_MASK);
> >  	free_irq(host->irq, host);
> > +	if (host->ops->disable_msi)
> > +		host->ops->disable_msi(host);
> >  
> >  	del_timer_sync(&host->timer);
> >  
> > diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h
> > index 0a3ed01..cbee843 100644
> > --- a/drivers/mmc/host/sdhci.h
> > +++ b/drivers/mmc/host/sdhci.h
> > @@ -296,6 +296,8 @@ struct sdhci_ops {
> >  	void    (*adma_workaround)(struct sdhci_host *host, u32 intmask);
> >  	void	(*platform_init)(struct sdhci_host *host);
> >  	void    (*card_event)(struct sdhci_host *host);
> > +	int	(*enable_msi)(struct sdhci_host *host, irq_handler_t handler);
> > +	void	(*disable_msi)(struct sdhci_host *host);
> >  };
> >  
> >  #ifdef CONFIG_MMC_SDHCI_IO_ACCESSORS
> > diff --git a/include/linux/mmc/sdhci.h b/include/linux/mmc/sdhci.h
> > index 3e781b8..3812479 100644
> > --- a/include/linux/mmc/sdhci.h
> > +++ b/include/linux/mmc/sdhci.h
> > @@ -99,6 +99,8 @@ struct sdhci_host {
> >  /* Controller has a non-standard host control register */
> >  #define SDHCI_QUIRK2_BROKEN_HOST_CONTROL		(1<<5)
> >  
> > +	bool msi_enabled;	/* SD host controller with PCI MSI enabled */
> > +
> >  	int irq;		/* Device IRQ */
> >  	void __iomem *ioaddr;	/* Mapped address */
> >  
> > 
> 
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