On 4/7/2020 12:26 AM, Manivannan Sadhasivam wrote:
On Mon, Apr 06, 2020 at 03:04:35PM -0600, Jeffrey Hugo wrote:
The MHI device may be in the syserr state when we attempt to init it in
power_up(). Since we have no local state, the handling is simple -
reset the device and wait for it to transition out of the reset state.
Signed-off-by: Jeffrey Hugo <jhugo@xxxxxxxxxxxxxx>
---
drivers/bus/mhi/core/pm.c | 20 ++++++++++++++++++++
1 file changed, 20 insertions(+)
diff --git a/drivers/bus/mhi/core/pm.c b/drivers/bus/mhi/core/pm.c
index 52690cb..cd6ba23 100644
--- a/drivers/bus/mhi/core/pm.c
+++ b/drivers/bus/mhi/core/pm.c
@@ -9,6 +9,7 @@
#include <linux/dma-direction.h>
#include <linux/dma-mapping.h>
#include <linux/interrupt.h>
+#include <linux/iopoll.h>
#include <linux/list.h>
#include <linux/mhi.h>
#include <linux/module.h>
@@ -760,6 +761,7 @@ static void mhi_deassert_dev_wake(struct mhi_controller *mhi_cntrl,
int mhi_async_power_up(struct mhi_controller *mhi_cntrl)
{
+ enum mhi_state state;
enum mhi_ee_type current_ee;
enum dev_st_transition next_state;
struct device *dev = &mhi_cntrl->mhi_dev->dev;
@@ -829,6 +831,24 @@ int mhi_async_power_up(struct mhi_controller *mhi_cntrl)
goto error_bhi_offset;
}
+ state = mhi_get_mhi_state(mhi_cntrl);
+ if (state == MHI_STATE_SYS_ERR) {
+ mhi_set_mhi_state(mhi_cntrl, MHI_STATE_RESET);
+ ret = readl_poll_timeout(mhi_cntrl->regs + MHICTRL, val,
+ !(val & MHICTRL_RESET_MASK), 1000,
Hmm. Do we really need a max 1ms delay between each read? I'd prefer to have
100ns to reduce the wait time.
I assume you mean 100us since that's the units of the parameter, and
usleep_range is the actual delay mechanism. Please correct me if that
is a bad assumption.
I chose 1ms to try to avoid flooding the bus, since on one system we
care about, the round trip time was observed to be ~1ms. However, that
is fairly arbitrary, so a factor of 10 reduction don't seem like a
significant issue.
+ mhi_cntrl->timeout_ms * 1000);
+ if (ret) {
+ dev_info(dev, "Failed to reset syserr\n");
dev_info(dev, "Failed to reset MHI due to syserr state\n"); ?
Ah yes, that is clearer. Thanks
--
Jeffrey Hugo
Qualcomm Technologies, Inc. is a member of the
Code Aurora Forum, a Linux Foundation Collaborative Project.
