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

[Aaron Lu <aaron.lu@intel.com>]

On 11/12/2013 05:27 PM, Jackey Shen wrote:
> 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;

If we call pci_enable_msi somewhere in sdhci_pci_probe_slot, then if it
failed, we can also fall back I suppose?

> 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.

The comments above free_irq says:

 *      on the card it drives before calling this function. The function
 *      does not return until any executing interrupts for this IRQ
 *      have completed.

It feels like a guard for the interrupt handler: after we call free_irq,
we are sure no interrupt hander is running(and since we have masked irq,
no more interrupt will occur either), so I suggest we keep it.

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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>