linux-kernel - Re: [RFC PATCH] pccard: configure CLS on attach

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Date:	Wed, 27 May 2009 08:03:28 -0600
From:	Matthew Wilcox <matthew@....cx>
To:	Tejun Heo <tj@...nel.org>
Cc:	Greg KH <greg@...ah.com>, Robert Hancock <hancockrwd@...il.com>,
	Alan Cox <alan@...rguk.ukuu.org.uk>, linux-pci@...r.kernel.org,
	Linux Kernel <linux-kernel@...r.kernel.org>, towerlexa@....de,
	Daniel Ritz <daniel.ritz@....ch>,
	Dominik Brodowski <linux@...inikbrodowski.net>,
	Kenji Kaneshige <kaneshige.kenji@...fujitsu.com>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Paul Mackerras <paulus@...ba.org>
Subject: Re: [RFC PATCH] pccard: configure CLS on attach

On Wed, May 27, 2009 at 10:32:45PM +0900, Tejun Heo wrote:
> THIS IS A RFC PATCH, SO NO SOB.  PLEASE DON'T APPLY YET.

This breaks CONFIG_PPC64, fwiw.  We'll want to stub out
pci_set_cacheline_size() for the PCI_DISABLE_MWI case too.

I don't know what PPC machines have Cardbus slots, presumably some
Macs do.  I don't know whether firmware takes care of configuring the
Cacheline Size register for Cardbus hotplug or not.  So we may want to
include pci_set_cacheline_size() in the !MWI build, or not.  Ben, Paul?

> towerlexa, can you please test this patch?
> 
> Cc: Daniel Ritz <daniel.ritz@....ch>
> Cc: Dominik Brodowski <linux@...inikbrodowski.net>
> Cc: Greg KH <greg@...ah.com>
> Cc: Kenji Kaneshige <kaneshige.kenji@...fujitsu.com>
> Cc: towerlexa@....de
> ---
>  drivers/pci/pci.c        |    3 +--
>  drivers/pcmcia/cardbus.c |   23 +++++++++++++++--------
>  include/linux/pci.h      |    1 +
>  3 files changed, 17 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index 1a91bf9..eafbe01 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -1860,8 +1860,7 @@ u8 pci_cache_line_size = PCI_CACHE_LINE_BYTES / 4;
>   *
>   * RETURNS: An appropriate -ERRNO error value on error, or zero for success.
>   */
> -static int
> -pci_set_cacheline_size(struct pci_dev *dev)
> +int pci_set_cacheline_size(struct pci_dev *dev)
>  {
>  	u8 cacheline_size;
>  
> diff --git a/drivers/pcmcia/cardbus.c b/drivers/pcmcia/cardbus.c
> index db77e1f..98789c0 100644
> --- a/drivers/pcmcia/cardbus.c
> +++ b/drivers/pcmcia/cardbus.c
> @@ -184,26 +184,33 @@ fail:
>      
>  =====================================================================*/
>  
> -/*
> - * Since there is only one interrupt available to CardBus
> - * devices, all devices downstream of this device must
> - * be using this IRQ.
> - */
> -static void cardbus_assign_irqs(struct pci_bus *bus, int irq)
> +static void cardbus_config_irq_and_cls(struct pci_bus *bus, int irq)
>  {
>  	struct pci_dev *dev;
>  
>  	list_for_each_entry(dev, &bus->devices, bus_list) {
>  		u8 irq_pin;
>  
> +		/*
> +		 * Since there is only one interrupt available to
> +		 * CardBus devices, all devices downstream of this
> +		 * device must be using this IRQ.
> +		 */
>  		pci_read_config_byte(dev, PCI_INTERRUPT_PIN, &irq_pin);
>  		if (irq_pin) {
>  			dev->irq = irq;
>  			pci_write_config_byte(dev, PCI_INTERRUPT_LINE, dev->irq);
>  		}
>  
> +		/*
> +		 * Some controllers transfer very slowly with 0 CLS.
> +		 * Configure it.  This may fail as CLS configuration
> +		 * is mandatory only for MWI.
> +		 */
> +		pci_set_cacheline_size(dev);
> +
>  		if (dev->subordinate)
> -			cardbus_assign_irqs(dev->subordinate, irq);
> +			cardbus_config_irq_and_cls(dev->subordinate, irq);
>  	}
>  }
>  
> @@ -228,7 +235,7 @@ int __ref cb_alloc(struct pcmcia_socket * s)
>  	 */
>  	pci_bus_size_bridges(bus);
>  	pci_bus_assign_resources(bus);
> -	cardbus_assign_irqs(bus, s->pci_irq);
> +	cardbus_config_irq_and_cls(bus, s->pci_irq);
>  
>  	/* socket specific tune function */
>  	if (s->tune_bridge)
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index 72698d8..e1a1aa6 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -688,6 +688,7 @@ void pci_disable_device(struct pci_dev *dev);
>  void pci_set_master(struct pci_dev *dev);
>  void pci_clear_master(struct pci_dev *dev);
>  int pci_set_pcie_reset_state(struct pci_dev *dev, enum pcie_reset_state state);
> +int pci_set_cacheline_size(struct pci_dev *dev);
>  #define HAVE_PCI_SET_MWI
>  int __must_check pci_set_mwi(struct pci_dev *dev);
>  int pci_try_set_mwi(struct pci_dev *dev);
> --
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-- 
Matthew Wilcox				Intel Open Source Technology Centre
"Bill, look, we understand that you're interested in selling us this
operating system, but compare it to ours.  We can't possibly take such
a retrograde step."
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