From: Jeffrey Hugo <jhugo@codeaurora.org>
To: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Cc: hemantk@codeaurora.org, linux-arm-msm@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/3] bus: mhi: core: Handle syserr during power_up
Date: Tue, 7 Apr 2020 09:11:33 -0600 [thread overview]
Message-ID: <f63b0a23-97d3-e690-70ae-a4485d42b28f@codeaurora.org> (raw)
In-Reply-To: <20200407062641.GC2442@Mani-XPS-13-9360>
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@codeaurora.org>
>> ---
>> 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.
next prev parent reply other threads:[~2020-04-07 15:11 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-06 21:04 [PATCH 0/3] Misc MHI fixes Jeffrey Hugo
2020-04-06 21:04 ` [PATCH 1/3] bus: mhi: core: Handle syserr during power_up Jeffrey Hugo
2020-04-07 6:26 ` Manivannan Sadhasivam
2020-04-07 15:11 ` Jeffrey Hugo [this message]
2020-04-07 15:32 ` Manivannan Sadhasivam
2020-04-06 21:04 ` [PATCH 2/3] bus: mhi: core: Make sure to powerdown if mhi_sync_power_up fails Jeffrey Hugo
2020-04-07 6:14 ` Manivannan Sadhasivam
2020-04-07 15:04 ` Jeffrey Hugo
2020-04-06 21:04 ` [PATCH 3/3] bus: mhi: core: Remove link_status() callback Jeffrey Hugo
2020-04-07 5:58 ` Manivannan Sadhasivam
2020-04-07 15:03 ` Jeffrey Hugo
2020-04-07 15:17 ` Manivannan Sadhasivam
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