Return-path: Received: from 128-177-27-249.ip.openhosting.com ([128.177.27.249]:36187 "EHLO jmalinen.user.openhosting.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754488AbZFPJDD (ORCPT ); Tue, 16 Jun 2009 05:03:03 -0400 Date: Tue, 16 Jun 2009 11:59:23 +0300 From: Jouni Malinen To: "John W. Linville" Cc: linux-wireless@vger.kernel.org, stable@kernel.org Subject: [PATCH] ath9k: Fix PCI FATAL interrupts by restoring RETRY_TIMEOUT disabling Message-ID: <20090616085922.GA10176@jm.kir.nu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-wireless-owner@vger.kernel.org List-ID: An earlier commit, b572b24c578ab1be9d1fcb11d2d8244878757a66, removed code that was documented to disable RETRY_TIMEOUT register (PCI reg 0x41) since it was claimed to be a no-op. However, it turns out that there are some combinations of hosts and ath9k-supported cards for which this is not a no-op (reg 0x41 has value 0x80, not 0) and this code (or something similar) is needed. In such cases, the driver may be next to unusable due to very frequent PCI FATAL interrupts from the card. Reverting the earlier commit, i.e., restoring the RETRY_TIMEOUT disabling, seems to resolve the issue. Since the removal of this code was not based on any known issue and was purely a cleanup change, the safest option here is to just revert that commit. Should there be desire to clean this up in the future, the change will need to be tested with a more complete coverage of cards and host systems. Cc: stable@kernel.org Signed-off-by: Jouni Malinen --- drivers/net/wireless/ath/ath9k/pci.c | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) This issue was a regression in 2.6.30 and this patch should be applied to wireless-testing.git and 2.6.31 as-is and to a 2.6.30.x stable release as-is but without the "ath/" subdirectory on the path. --- wireless-testing.orig/drivers/net/wireless/ath/ath9k/pci.c 2009-06-16 11:38:16.000000000 +0300 +++ wireless-testing/drivers/net/wireless/ath/ath9k/pci.c 2009-06-16 11:38:29.000000000 +0300 @@ -87,6 +87,7 @@ static int ath_pci_probe(struct pci_dev struct ath_softc *sc; struct ieee80211_hw *hw; u8 csz; + u32 val; int ret = 0; struct ath_hw *ah; @@ -133,6 +134,14 @@ static int ath_pci_probe(struct pci_dev pci_set_master(pdev); + /* + * Disable the RETRY_TIMEOUT register (0x41) to keep + * PCI Tx retries from interfering with C3 CPU state. + */ + pci_read_config_dword(pdev, 0x40, &val); + if ((val & 0x0000ff00) != 0) + pci_write_config_dword(pdev, 0x40, val & 0xffff00ff); + ret = pci_request_region(pdev, 0, "ath9k"); if (ret) { dev_err(&pdev->dev, "PCI memory region reserve error\n"); @@ -239,12 +248,21 @@ static int ath_pci_resume(struct pci_dev struct ieee80211_hw *hw = pci_get_drvdata(pdev); struct ath_wiphy *aphy = hw->priv; struct ath_softc *sc = aphy->sc; + u32 val; int err; err = pci_enable_device(pdev); if (err) return err; pci_restore_state(pdev); + /* + * Suspend/Resume resets the PCI configuration space, so we have to + * re-disable the RETRY_TIMEOUT register (0x41) to keep + * PCI Tx retries from interfering with C3 CPU state + */ + pci_read_config_dword(pdev, 0x40, &val); + if ((val & 0x0000ff00) != 0) + pci_write_config_dword(pdev, 0x40, val & 0xffff00ff); /* Enable LED */ ath9k_hw_cfg_output(sc->sc_ah, ATH_LED_PIN, -- Jouni Malinen PGP id EFC895FA