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[netdrvr] tulip: Better MWI workaround for 21143 rev 65 chip errata 

This patch works around the MWI bug on the DC21143 rev 65 Tulip by
ensuring that the receive buffers don't end on a cache line boundary
(as documented in the errata).

This patch is required for the MIPS based Cobalt Qube/RaQ as
supporting the extra PCI commands seems to reduce the chance of a hard
lockup between the Tulip and the PCI bridge.

Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
This commit is contained in:
Peter Horton 2008-03-25 12:39:09 +01:00 committed by Jeff Garzik
parent 48dd59e398
commit 10c6462090
2 changed files with 11 additions and 15 deletions
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7
drivers/net/tulip/tulip.h
View File

@ -268,7 +268,12 @@ enum t21143_csr6_bits {
#define RX_RING_SIZE 128
#define MEDIA_MASK 31
#define PKT_BUF_SZ 1536 /* Size of each temporary Rx buffer. */
/* The receiver on the DC21143 rev 65 can fail to close the last
* receive descriptor in certain circumstances (see errata) when
* using MWI. This can only occur if the receive buffer ends on
* a cache line boundary, so the "+ 4" below ensures it doesn't.
*/
#define PKT_BUF_SZ (1536 + 4) /* Size of each temporary Rx buffer. */
#define TULIP_MIN_CACHE_LINE 8 /* in units of 32-bit words */

19
drivers/net/tulip/tulip_core.c
View File

@ -1154,18 +1154,13 @@ static void __devinit tulip_mwi_config (struct pci_dev *pdev,
tp->csr0 = csr0 = 0;
/* if we have any cache line size at all, we can do MRM */
csr0 |= MRM;
/* if we have any cache line size at all, we can do MRM and MWI */
csr0 |= MRM | MWI;
/* ...and barring hardware bugs, MWI */
if (!(tp->chip_id == DC21143 && tp->revision == 65))
csr0 |= MWI;
/* set or disable MWI in the standard PCI command bit.
* Check for the case where mwi is desired but not available
/* Enable MWI in the standard PCI command bit.
* Check for the case where MWI is desired but not available
*/
if (csr0 & MWI) pci_try_set_mwi(pdev);
else pci_clear_mwi(pdev);
pci_try_set_mwi(pdev);
/* read result from hardware (in case bit refused to enable) */
pci_read_config_word(pdev, PCI_COMMAND, &pci_command);
@ -1401,10 +1396,6 @@ static int __devinit tulip_init_one (struct pci_dev *pdev,
#ifdef CONFIG_TULIP_MWI
if (!force_csr0 && (tp->flags & HAS_PCI_MWI))
tulip_mwi_config (pdev, dev);
#else
/* MWI is broken for DC21143 rev 65... */
if (chip_idx == DC21143 && pdev->revision == 65)
tp->csr0 &= ~MWI;
#endif
/* Stop the chip's Tx and Rx processes. */