This is a note to let you know that I've just added the patch titled
USB: EHCI: tegra: set txfill_tuning
to my usb git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git
in the usb-linus branch.
The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)
The patch will hopefully also be merged in Linus's tree for the
next -rc kernel release.
If you have any questions about this process, please let me know.
>From 4f2fe2d27472f4a5dbd875888af4fc5175f3fdc5 Mon Sep 17 00:00:00 2001
From: Stephen Warren <swarren@xxxxxxxxxx>
Date: Mon, 14 Apr 2014 15:21:23 -0600
Subject: 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@xxxxxxxxxxxxxxx> # 3.14+
Signed-off-by: Stephen Warren <swarren@xxxxxxxxxx>
Acked-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
Tested-by: Alexandre Courbot <acourbot@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/usb/host/ehci-tegra.c | 23 +++++++++++++++++++++++
1 file changed, 23 insertions(+)
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)
--
1.9.0
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