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linux-ti33x-psp: Check if scheduling is required after DMA

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After processing one DMA completion, checking if rescheduling is
required instead of scheduling another completion request if the
FIFO is non empty.

This fixes high CPU load issue seen with g_mass_storage on a beaglebone
and could potentially fix similar issues seen with other gadget drivers

Signed-off-by: Joel A Fernandes <joelagnel@ti.com>
Signed-off-by: Koen Kooi <koen@dominion.thruhere.net>
This commit is contained in:
Joel A Fernandes
2011-11-13 09:11:18 -06:00
committed by Koen Kooi
parent 77208efef6
commit c4310e7216
2 changed files with 44 additions and 1 deletions
Download Patch File Download Diff File Expand all files Collapse all files

42
recipes-kernel/linux/linux-ti33x-psp-3.1/0006-usb-musb-cppi41_dma-Check-if-scheduling-is-required-.patch Normal file
View File

@@ -0,0 +1,42 @@
From b564457d26931a00f8c5645981a00c1eb78e9a90 Mon Sep 17 00:00:00 2001
From: Joel A Fernandes <joelagnel@ti.com>
Date: Sat, 12 Nov 2011 23:42:26 -0600
Subject: [PATCH] usb::musb::cppi41_dma: Check if scheduling is required after DMA
Even after TX DMA, data can still be in the FIFO and we would keep
rescheduling the worker thread in a polling fashion taking up a lot
of CPU if the controller was slow to respond. We check if rescheduling
is required and sleep if so.
This fixes high CPU load issue seen with g_mass_storage on a BeagleBone
and could potentially fix similar issues seen with other gadget drivers.
Signed-off-by: Joel A Fernandes <joelagnel@ti.com>
---
drivers/usb/musb/cppi41_dma.c | 10 ++++++++++
1 files changed, 10 insertions(+), 0 deletions(-)
diff --git a/drivers/usb/musb/cppi41_dma.c b/drivers/usb/musb/cppi41_dma.c
index a24707c..e68c5d7 100644
--- a/drivers/usb/musb/cppi41_dma.c
+++ b/drivers/usb/musb/cppi41_dma.c
@@ -1319,6 +1319,16 @@ void txdma_completion_work(struct work_struct *data)
struct musb *musb = cppi->musb;
unsigned long flags;
+ /*
+ * txdma worker thread can call schedule_work on itself and cause
+ * itself to be scheduled immediately and because the data might still
+ * be in FIFO if it hasn't been pushed out after DMA, it is possible for
+ * the worker to consume lot of CPU when the controller is slow, so we
+ * reschedule if necessary.
+ */
+ if (need_resched())
+ cond_resched();
+
spin_lock_irqsave(&musb->lock, flags);
cppi41_check_fifo_empty(cppi);
spin_unlock_irqrestore(&musb->lock, flags);
--
1.7.4.1

3
recipes-kernel/linux/linux-ti33x-psp_3.1.bb
View File

@@ -11,7 +11,7 @@ MULTI_CONFIG_BASE_SUFFIX = ""
BRANCH = "v3.1-staging"
SRCREV = "1d84d8853fa30cf3db2571a5aec572accca4e29d"
MACHINE_KERNEL_PR_append = "q+gitr${SRCREV}"
MACHINE_KERNEL_PR_append = "r+gitr${SRCREV}"
COMPATIBLE_MACHINE = "(ti33x)"
@@ -35,6 +35,7 @@ PATCHES_OVER_PSP = " \
file://0003-arm-omap-mcspi-correct-memory-range-when-requesting-.patch \
file://0004-arm-omap-mcspi-follow-proper-pm_runtime-enable-disab.patch \
file://0005-arm-omap-mcspi-follow-proper-probe-remove-steps.patch \
file://0006-usb-musb-cppi41_dma-Check-if-scheduling-is-required-.patch \
file://can/0001-can-d_can-Added-support-for-Bosch-D_CAN-controller.patch \
file://can/0002-can-d_can-Added-platform-data-for-am33xx-device.patch \
file://can/0003-can-d_can-DCAN-config-added-to-am335x_evm_defconfig.patch \