[RFC/PATCH -mm] add pci_try_set_mwi

From: Randy Dunlap
Date: Mon Apr 16 2007 - 13:19:03 EST

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[resend, chaning linux-ide to lkml]

On Thu, 5 Apr 2007 14:20:01 -0700 Andrew Morton wrote:

> hm. Well, what to do?
>
> How about we prevail upon Randy to:
>
> - rename pci_set_mwi() to pci_try_set_mwi()
>
> - make it return 0 on success, 1 if the "try" failed
>
> - make it return -EFOO on error (presently unimplemented)
>
> - review callers
>
> - remove __must_check
>
> ?

From: Randy Dunlap <randy.dunlap@xxxxxxxxxx>

As suggested by Andrew, add pci_try_set_mwi(), which does not require
return-value checking.

- add pci_try_set_mwi() without __must_check
- make it return 0 on success, errno if the "try" failed or error
- review callers

Signed-off-by: Randy Dunlap <randy.dunlap@xxxxxxxxxx>
---
Documentation/pci.txt | 5 +++-
drivers/ata/pata_cs5530.c | 2 -
drivers/ide/pci/cs5530.c | 2 -
drivers/net/cassini.c | 4 +--
drivers/net/starfire.c | 2 -
drivers/net/tulip/tulip_core.c | 2 -
drivers/net/wireless/mac80211/p54/prism54pci.c | 2 -
drivers/net/wireless/prism54/islpci_hotplug.c | 3 --
drivers/pci/pci.c | 28 +++++++++++++++++++++----
drivers/scsi/lpfc/lpfc_init.c | 5 ----
drivers/usb/gadget/net2280.c | 2 -
include/linux/pci.h | 1
12 files changed, 39 insertions(+), 19 deletions(-)

--- linux-2.6.21-rc6-mm1.orig/include/linux/pci.h
+++ linux-2.6.21-rc6-mm1/include/linux/pci.h
@@ -547,6 +547,7 @@ void pci_set_master(struct pci_dev *dev)
int pci_set_pcie_reset_state(struct pci_dev *dev, enum pcie_reset_state state);
#define HAVE_PCI_SET_MWI
int __must_check pci_set_mwi(struct pci_dev *dev);
+int pci_try_set_mwi(struct pci_dev *dev);
void pci_clear_mwi(struct pci_dev *dev);
void pci_intx(struct pci_dev *dev, int enable);
void pci_msi_off(struct pci_dev *dev);
--- linux-2.6.21-rc6-mm1.orig/drivers/pci/pci.c
+++ linux-2.6.21-rc6-mm1/drivers/pci/pci.c
@@ -1162,6 +1162,11 @@ int pci_set_mwi(struct pci_dev *dev)
return 0;
}

+int pci_try_set_mwi(struct pci_dev *dev)
+{
+ return 0;
+}
+
void pci_clear_mwi(struct pci_dev *dev)
{
}
@@ -1218,9 +1223,7 @@ pci_set_cacheline_size(struct pci_dev *d
* pci_set_mwi - enables memory-write-invalidate PCI transaction
* @dev: the PCI device for which MWI is enabled
*
- * Enables the Memory-Write-Invalidate transaction in %PCI_COMMAND,
- * and then calls @pcibios_set_mwi to do the needed arch specific
- * operations or a generic mwi-prep function.
+ * Enables the Memory-Write-Invalidate transaction in %PCI_COMMAND.
*
* RETURNS: An appropriate -ERRNO error value on error, or zero for success.
*/
@@ -1236,7 +1239,8 @@ pci_set_mwi(struct pci_dev *dev)

pci_read_config_word(dev, PCI_COMMAND, &cmd);
if (! (cmd & PCI_COMMAND_INVALIDATE)) {
- pr_debug("PCI: Enabling Mem-Wr-Inval for device %s\n", pci_name(dev));
+ pr_debug("PCI: Enabling Mem-Wr-Inval for device %s\n",
+ pci_name(dev));
cmd |= PCI_COMMAND_INVALIDATE;
pci_write_config_word(dev, PCI_COMMAND, cmd);
}
@@ -1245,6 +1249,21 @@ pci_set_mwi(struct pci_dev *dev)
}

/**
+ * pci_try_set_mwi - enables memory-write-invalidate PCI transaction
+ * @dev: the PCI device for which MWI is enabled
+ *
+ * Enables the Memory-Write-Invalidate transaction in %PCI_COMMAND.
+ * Callers are not required to check the return value.
+ *
+ * RETURNS: An appropriate -ERRNO error value on error, or zero for success.
+ */
+int pci_try_set_mwi(struct pci_dev *dev)
+{
+ int rc = pci_set_mwi(dev);
+ return rc;
+}
+
+/**
* pci_clear_mwi - disables Memory-Write-Invalidate for device dev
* @dev: the PCI device to disable
*
@@ -1418,6 +1437,7 @@ EXPORT_SYMBOL(pci_release_selected_regio
EXPORT_SYMBOL(pci_request_selected_regions);
EXPORT_SYMBOL(pci_set_master);
EXPORT_SYMBOL(pci_set_mwi);
+EXPORT_SYMBOL(pci_try_set_mwi);
EXPORT_SYMBOL(pci_clear_mwi);
EXPORT_SYMBOL_GPL(pci_intx);
EXPORT_SYMBOL(pci_set_dma_mask);
--- linux-2.6.21-rc6-mm1.orig/drivers/ata/pata_cs5530.c
+++ linux-2.6.21-rc6-mm1/drivers/ata/pata_cs5530.c
@@ -270,7 +270,7 @@ static int cs5530_init_chip(void)
}

pci_set_master(cs5530_0);
- pci_set_mwi(cs5530_0);
+ pci_try_set_mwi(cs5530_0);

/*
* Set PCI CacheLineSize to 16-bytes:
--- linux-2.6.21-rc6-mm1.orig/drivers/ide/pci/cs5530.c
+++ linux-2.6.21-rc6-mm1/drivers/ide/pci/cs5530.c
@@ -236,7 +236,7 @@ static unsigned int __devinit init_chips
*/

pci_set_master(cs5530_0);
- pci_set_mwi(cs5530_0);
+ pci_try_set_mwi(cs5530_0);

/*
* Set PCI CacheLineSize to 16-bytes:
--- linux-2.6.21-rc6-mm1.orig/drivers/usb/gadget/net2280.c
+++ linux-2.6.21-rc6-mm1/drivers/usb/gadget/net2280.c
@@ -2964,7 +2964,7 @@ static int net2280_probe (struct pci_dev
, &dev->pci->pcimstctl);
/* erratum 0115 shouldn't appear: Linux inits PCI_LATENCY_TIMER */
pci_set_master (pdev);
- pci_set_mwi (pdev);
+ pci_try_set_mwi (pdev);

/* ... also flushes any posted pci writes */
dev->chiprev = get_idx_reg (dev->regs, REG_CHIPREV) & 0xffff;
--- linux-2.6.21-rc6-mm1.orig/drivers/scsi/lpfc/lpfc_init.c
+++ linux-2.6.21-rc6-mm1/drivers/scsi/lpfc/lpfc_init.c
@@ -1494,10 +1494,7 @@ lpfc_pci_probe_one(struct pci_dev *pdev,

pci_set_master(pdev);
- retval = pci_set_mwi(pdev);
- if (retval)
- dev_printk(KERN_WARNING, &pdev->dev,
- "Warning: pci_set_mwi returned %d\n", retval);
+ pci_try_set_mwi(pdev);

if (pci_set_dma_mask(phba->pcidev, DMA_64BIT_MASK) != 0)
if (pci_set_dma_mask(phba->pcidev, DMA_32BIT_MASK) != 0)
--- linux-2.6.21-rc6-mm1.orig/drivers/net/wireless/prism54/islpci_hotplug.c
+++ linux-2.6.21-rc6-mm1/drivers/net/wireless/prism54/islpci_hotplug.c
@@ -167,8 +167,7 @@ prism54_probe(struct pci_dev *pdev, cons
pci_set_master(pdev);

/* enable MWI */
- if (!pci_set_mwi(pdev))
- printk(KERN_INFO "%s: pci_set_mwi(pdev) succeeded\n", DRV_NAME);
+ pci_try_set_mwi(pdev);

/* setup the network device interface and its structure */
if (!(ndev = islpci_setup(pdev))) {
--- linux-2.6.21-rc6-mm1.orig/drivers/net/cassini.c
+++ linux-2.6.21-rc6-mm1/drivers/net/cassini.c
@@ -4919,10 +4919,10 @@ static int __devinit cas_init_one(struct
pci_cmd &= ~PCI_COMMAND_SERR;
pci_cmd |= PCI_COMMAND_PARITY;
pci_write_config_word(pdev, PCI_COMMAND, pci_cmd);
- pci_set_mwi(pdev);
+ pci_try_set_mwi(pdev);
/*
* On some architectures, the default cache line size set
- * by pci_set_mwi reduces perforamnce. We have to increase
+ * by pci_set_mwi reduces performance. We have to increase
* it for this case. To start, we'll print some configuration
* data.
*/
--- linux-2.6.21-rc6-mm1.orig/drivers/net/starfire.c
+++ linux-2.6.21-rc6-mm1/drivers/net/starfire.c
@@ -740,7 +740,7 @@ static int __devinit starfire_init_one(s
pci_set_master(pdev);

/* enable MWI -- it vastly improves Rx performance on sparc64 */
- pci_set_mwi(pdev);
+ pci_try_set_mwi(pdev);

#ifdef ZEROCOPY
/* Starfire can do TCP/UDP checksumming */
--- linux-2.6.21-rc6-mm1.orig/drivers/net/tulip/tulip_core.c
+++ linux-2.6.21-rc6-mm1/drivers/net/tulip/tulip_core.c
@@ -1155,7 +1155,7 @@ static void __devinit tulip_mwi_config (
/* set or disable MWI in the standard PCI command bit.
* Check for the case where mwi is desired but not available
*/
- if (csr0 & MWI) pci_set_mwi(pdev);
+ if (csr0 & MWI) pci_try_set_mwi(pdev);
else pci_clear_mwi(pdev);

/* read result from hardware (in case bit refused to enable) */
--- linux-2.6.21-rc6-mm1.orig/drivers/net/wireless/mac80211/p54/prism54pci.c
+++ linux-2.6.21-rc6-mm1/drivers/net/wireless/mac80211/p54/prism54pci.c
@@ -539,7 +539,7 @@ static int __devinit p54p_probe(struct p
}

pci_set_master(pdev);
- pci_set_mwi(pdev);
+ pci_try_set_mwi(pdev);

pci_write_config_byte(pdev, 0x40, 0);
pci_write_config_byte(pdev, 0x41, 0);
--- linux-2.6.21-rc6-mm1.orig/Documentation/pci.txt
+++ linux-2.6.21-rc6-mm1/Documentation/pci.txt
@@ -299,7 +299,10 @@ If the PCI device can use the PCI Memory
call pci_set_mwi(). This enables the PCI_COMMAND bit for Mem-Wr-Inval
and also ensures that the cache line size register is set correctly.
Check the return value of pci_set_mwi() as not all architectures
-or chip-sets may support Memory-Write-Invalidate.
+or chip-sets may support Memory-Write-Invalidate. Alternatively,
+if Mem-Wr-Inval would be nice to have but is not required, call
+pci_try_set_mwi() to have the system do its best effort at enabling
+Mem-Wr-Inval.

3.2 Request MMIO/IOP resources
-
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Next message: Adrian Bunk: "Re: ZFS with Linux: An Open Plea"
Previous message: Randy Dunlap: "Re: [nameidata 2/2] Pass no useless nameidata to the create, lookup,and permission IOPs"
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