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authorStephen Warren <swarren@nvidia.com>2014-04-14 15:21:23 -0600
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-04-16 13:59:13 -0700
commit4f2fe2d27472f4a5dbd875888af4fc5175f3fdc5 (patch)
treebf93520a69ccb388c052924bde8667cbbf3ddfff /drivers/usb
parente155b5b8d2d42455d3a94c2460c287e97184ec61 (diff)
downloadlinux-4f2fe2d27472f4a5dbd875888af4fc5175f3fdc5.tar.bz2
USB: EHCI: tegra: set txfill_tuning
To avoid memory fetch underflows with larger USB transfers, Tegra SoCs need txfill_tuning's txfifothresh register field set to a non-default value. Add a custom reset override in order to set this up. These values are recommended practice for all Tegra chips. However, I've only noticed practical problems when not setting them this way on systems using Tegra124. Hence, CC: stable only for recent kernels which actually support Tegra124. Cc: <stable@vger.kernel.org> # 3.14+ Signed-off-by: Stephen Warren <swarren@nvidia.com> Acked-by: Alan Stern <stern@rowland.harvard.edu> Tested-by: Alexandre Courbot <acourbot@nvidia.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/usb')
-rw-r--r--drivers/usb/host/ehci-tegra.c23
1 files changed, 23 insertions, 0 deletions
diff --git a/drivers/usb/host/ehci-tegra.c b/drivers/usb/host/ehci-tegra.c
index 27ac6ad53c3d..7ef00ecb0da1 100644
--- a/drivers/usb/host/ehci-tegra.c
+++ b/drivers/usb/host/ehci-tegra.c
@@ -509,8 +509,31 @@ static struct platform_driver tegra_ehci_driver = {
}
};
+static int tegra_ehci_reset(struct usb_hcd *hcd)
+{
+ struct ehci_hcd *ehci = hcd_to_ehci(hcd);
+ int retval;
+ int txfifothresh;
+
+ retval = ehci_setup(hcd);
+ if (retval)
+ return retval;
+
+ /*
+ * We should really pull this value out of tegra_ehci_soc_config, but
+ * to avoid needing access to it, make use of the fact that Tegra20 is
+ * the only one so far that needs a value of 10, and Tegra20 is the
+ * only one which doesn't set has_hostpc.
+ */
+ txfifothresh = ehci->has_hostpc ? 0x10 : 10;
+ ehci_writel(ehci, txfifothresh << 16, &ehci->regs->txfill_tuning);
+
+ return 0;
+}
+
static const struct ehci_driver_overrides tegra_overrides __initconst = {
.extra_priv_size = sizeof(struct tegra_ehci_hcd),
+ .reset = tegra_ehci_reset,
};
static int __init ehci_tegra_init(void)