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SubjectRe: [PATCH v6 3/8] bus: mhi: core: Improvements to the channel handling state machine
Hi Mani,

On 2021-02-24 02:03 AM, Manivannan Sadhasivam wrote:
> On Thu, Feb 04, 2021 at 12:28:01PM -0800, Bhaumik Bhatt wrote:
>> Improve the channel handling state machine such that all commands
>> go through a common function and validation process to ensure
>> that the state machine is not violated in any way and adheres to
>> the MHI specification. Assert device wake before sending the
>> channel update commands instead of a wake toggle to ensure we
>> fail if device is in a bad state. Also update print messages to
>> use client device to accurately represent the channel being
>> updated.
>>
>
> This patch is doing atleast 3 things and that is not acceptable. Please
> split this patch and send.
>
These changes to commit text and other updates were done after your
comments for v5
[1].

Please check and let me know what you think. I have addressed them and
added info
in the commit description.

I feel this is one patch to improve channel handling overall, so the
"assert device wake"
change is part of that and I have stated that.

> Thanks,
> Mani
>
>> Signed-off-by: Bhaumik Bhatt <bbhatt@codeaurora.org>
>> Reviewed-by: Hemant Kumar <hemantk@codeaurora.org>
>> ---
>> drivers/bus/mhi/core/init.c | 6 ++
>> drivers/bus/mhi/core/internal.h | 12 +++
>> drivers/bus/mhi/core/main.c | 172
>> ++++++++++++++++++++++------------------
>> 3 files changed, 114 insertions(+), 76 deletions(-)
>>
>> diff --git a/drivers/bus/mhi/core/init.c b/drivers/bus/mhi/core/init.c
>> index 03c5786..482b365 100644
>> --- a/drivers/bus/mhi/core/init.c
>> +++ b/drivers/bus/mhi/core/init.c
>> @@ -54,6 +54,12 @@ const char * const mhi_state_str[MHI_STATE_MAX] = {
>> [MHI_STATE_SYS_ERR] = "SYS_ERR",
>> };
>>
>> +const char * const mhi_ch_state_type_str[MHI_CH_STATE_TYPE_MAX] = {
>> + [MHI_CH_STATE_TYPE_RESET] = "RESET",
>> + [MHI_CH_STATE_TYPE_STOP] = "STOP",
>> + [MHI_CH_STATE_TYPE_START] = "START",
>> +};
>> +
>> static const char * const mhi_pm_state_str[] = {
>> [MHI_PM_STATE_DISABLE] = "DISABLE",
>> [MHI_PM_STATE_POR] = "POR",
>> diff --git a/drivers/bus/mhi/core/internal.h
>> b/drivers/bus/mhi/core/internal.h
>> index 6f80ec3..7e3aac1 100644
>> --- a/drivers/bus/mhi/core/internal.h
>> +++ b/drivers/bus/mhi/core/internal.h
>> @@ -369,6 +369,18 @@ enum mhi_ch_state {
>> MHI_CH_STATE_ERROR = 0x5,
>> };
>>
>> +enum mhi_ch_state_type {
>> + MHI_CH_STATE_TYPE_RESET,
>> + MHI_CH_STATE_TYPE_STOP,
>> + MHI_CH_STATE_TYPE_START,
>> + MHI_CH_STATE_TYPE_MAX,
>> +};
>> +
>> +extern const char * const
>> mhi_ch_state_type_str[MHI_CH_STATE_TYPE_MAX];
>> +#define TO_CH_STATE_TYPE_STR(state) (((state) >=
>> MHI_CH_STATE_TYPE_MAX) ? \
>> + "INVALID_STATE" : \
>> + mhi_ch_state_type_str[(state)])
>> +
>> #define MHI_INVALID_BRSTMODE(mode) (mode != MHI_DB_BRST_DISABLE && \
>> mode != MHI_DB_BRST_ENABLE)
>>
>> diff --git a/drivers/bus/mhi/core/main.c b/drivers/bus/mhi/core/main.c
>> index d068188..2f6fdb2 100644
>> --- a/drivers/bus/mhi/core/main.c
>> +++ b/drivers/bus/mhi/core/main.c
>> @@ -1188,56 +1188,114 @@ int mhi_send_cmd(struct mhi_controller
>> *mhi_cntrl,
>> return 0;
>> }
>>
>> -static void __mhi_unprepare_channel(struct mhi_controller *mhi_cntrl,
>> - struct mhi_chan *mhi_chan)
>> +static int mhi_update_channel_state(struct mhi_controller *mhi_cntrl,
>> + struct mhi_chan *mhi_chan,
>> + enum mhi_ch_state_type to_state)
>> {
>> - int ret;
>> - struct device *dev = &mhi_cntrl->mhi_dev->dev;
>> + struct device *dev = &mhi_chan->mhi_dev->dev;
>> + enum mhi_cmd_type cmd = MHI_CMD_NOP;
>> + int ret = -EIO;
>> +
>> + dev_dbg(dev, "%d: Updating channel state to: %s\n", mhi_chan->chan,
>> + TO_CH_STATE_TYPE_STR(to_state));
>> +
>> + switch (to_state) {
>> + case MHI_CH_STATE_TYPE_RESET:
>> + write_lock_irq(&mhi_chan->lock);
>> + if (mhi_chan->ch_state != MHI_CH_STATE_STOP &&
>> + mhi_chan->ch_state != MHI_CH_STATE_ENABLED &&
>> + mhi_chan->ch_state != MHI_CH_STATE_SUSPENDED) {
>> + write_unlock_irq(&mhi_chan->lock);
>> + return -EINVAL;
>> + }
>> + mhi_chan->ch_state = MHI_CH_STATE_DISABLED;
>> + write_unlock_irq(&mhi_chan->lock);
>>
>> - dev_dbg(dev, "Entered: unprepare channel:%d\n", mhi_chan->chan);
>> + cmd = MHI_CMD_RESET_CHAN;
>> + break;
>> + case MHI_CH_STATE_TYPE_STOP:
>> + if (mhi_chan->ch_state != MHI_CH_STATE_ENABLED)
>> + return -EINVAL;
>>
>> - /* no more processing events for this channel */
>> - mutex_lock(&mhi_chan->mutex);
>> - write_lock_irq(&mhi_chan->lock);
>> - if (mhi_chan->ch_state != MHI_CH_STATE_ENABLED &&
>> - mhi_chan->ch_state != MHI_CH_STATE_SUSPENDED) {
>> - write_unlock_irq(&mhi_chan->lock);
>> - mutex_unlock(&mhi_chan->mutex);
>> - return;
>> + cmd = MHI_CMD_STOP_CHAN;
>> + break;
>> + case MHI_CH_STATE_TYPE_START:
>> + if (mhi_chan->ch_state != MHI_CH_STATE_STOP &&
>> + mhi_chan->ch_state != MHI_CH_STATE_DISABLED)
>> + return -EINVAL;
>> +
>> + cmd = MHI_CMD_START_CHAN;
>> + break;
>> + default:
>> + dev_err(dev, "%d: Channel state update to %s not allowed\n",
>> + mhi_chan->chan, TO_CH_STATE_TYPE_STR(to_state));
>> + return -EINVAL;
>> }
>>
>> - mhi_chan->ch_state = MHI_CH_STATE_DISABLED;
>> - write_unlock_irq(&mhi_chan->lock);
>> + /* bring host and device out of suspended states */
>> + ret = mhi_device_get_sync(mhi_cntrl->mhi_dev);
>> + if (ret)
>> + return ret;
>> + mhi_cntrl->runtime_get(mhi_cntrl);
>>
>> reinit_completion(&mhi_chan->completion);
>> - read_lock_bh(&mhi_cntrl->pm_lock);
>> - if (MHI_PM_IN_ERROR_STATE(mhi_cntrl->pm_state)) {
>> - read_unlock_bh(&mhi_cntrl->pm_lock);
>> - goto error_invalid_state;
>> + ret = mhi_send_cmd(mhi_cntrl, mhi_chan, cmd);
>> + if (ret) {
>> + dev_err(dev, "%d: Failed to send %s channel command\n",
>> + mhi_chan->chan, TO_CH_STATE_TYPE_STR(to_state));
>> + goto exit_channel_update;
>> }
>>
>> - mhi_cntrl->wake_toggle(mhi_cntrl);
>> - read_unlock_bh(&mhi_cntrl->pm_lock);
>> + ret = wait_for_completion_timeout(&mhi_chan->completion,
>> + msecs_to_jiffies(mhi_cntrl->timeout_ms));
>> + if (!ret || mhi_chan->ccs != MHI_EV_CC_SUCCESS) {
>> + dev_err(dev,
>> + "%d: Failed to receive %s channel command completion\n",
>> + mhi_chan->chan, TO_CH_STATE_TYPE_STR(to_state));
>> + ret = -EIO;
>> + goto exit_channel_update;
>> + }
>>
>> - mhi_cntrl->runtime_get(mhi_cntrl);
>> + ret = 0;
>> +
>> + if (to_state != MHI_CH_STATE_TYPE_RESET) {
>> + write_lock_irq(&mhi_chan->lock);
>> + mhi_chan->ch_state = (to_state == MHI_CH_STATE_TYPE_START) ?
>> + MHI_CH_STATE_ENABLED : MHI_CH_STATE_STOP;
>> + write_unlock_irq(&mhi_chan->lock);
>> + }
>> +
>> + dev_dbg(dev, "%d: Channel state change to %s successful\n",
>> + mhi_chan->chan, TO_CH_STATE_TYPE_STR(to_state));
>> +
>> +exit_channel_update:
>> mhi_cntrl->runtime_put(mhi_cntrl);
>> - ret = mhi_send_cmd(mhi_cntrl, mhi_chan, MHI_CMD_RESET_CHAN);
>> - if (ret)
>> - goto error_invalid_state;
>> + mhi_device_put(mhi_cntrl->mhi_dev);
>>
>> - /* even if it fails we will still reset */
>> - ret = wait_for_completion_timeout(&mhi_chan->completion,
>> - msecs_to_jiffies(mhi_cntrl->timeout_ms));
>> - if (!ret || mhi_chan->ccs != MHI_EV_CC_SUCCESS)
>> - dev_err(dev,
>> - "Failed to receive cmd completion, still resetting\n");
>> + return ret;
>> +}
>> +
>> +static void __mhi_unprepare_channel(struct mhi_controller *mhi_cntrl,
>> + struct mhi_chan *mhi_chan)
>> +{
>> + int ret;
>> + struct device *dev = &mhi_chan->mhi_dev->dev;
>> +
>> + mutex_lock(&mhi_chan->mutex);
>> +
>> + /* no more processing events for this channel */
>> + ret = mhi_update_channel_state(mhi_cntrl, mhi_chan,
>> + MHI_CH_STATE_TYPE_RESET);
>> + if (ret)
>> + dev_err(dev, "%d: Failed to reset channel, still resetting\n",
>> + mhi_chan->chan);
>>
>> -error_invalid_state:
>> if (!mhi_chan->offload_ch) {
>> mhi_reset_chan(mhi_cntrl, mhi_chan);
>> mhi_deinit_chan_ctxt(mhi_cntrl, mhi_chan);
>> }
>> - dev_dbg(dev, "chan:%d successfully resetted\n", mhi_chan->chan);
>> + dev_dbg(dev, "%d: successfully reset\n", mhi_chan->chan);
>> +
>> mutex_unlock(&mhi_chan->mutex);
>> }
>>
>> @@ -1245,28 +1303,16 @@ int mhi_prepare_channel(struct mhi_controller
>> *mhi_cntrl,
>> struct mhi_chan *mhi_chan)
>> {
>> int ret = 0;
>> - struct device *dev = &mhi_cntrl->mhi_dev->dev;
>> -
>> - dev_dbg(dev, "Preparing channel: %d\n", mhi_chan->chan);
>> + struct device *dev = &mhi_chan->mhi_dev->dev;
>>
>> if (!(BIT(mhi_cntrl->ee) & mhi_chan->ee_mask)) {
>> - dev_err(dev,
>> - "Current EE: %s Required EE Mask: 0x%x for chan: %s\n",
>> - TO_MHI_EXEC_STR(mhi_cntrl->ee), mhi_chan->ee_mask,
>> - mhi_chan->name);
>> + dev_err(dev, "Current EE: %s Required EE Mask: 0x%x\n",
>> + TO_MHI_EXEC_STR(mhi_cntrl->ee), mhi_chan->ee_mask);
>> return -ENOTCONN;
>> }
>>
>> mutex_lock(&mhi_chan->mutex);
>>
>> - /* If channel is not in disable state, do not allow it to start */
>> - if (mhi_chan->ch_state != MHI_CH_STATE_DISABLED) {
>> - ret = -EIO;
>> - dev_dbg(dev, "channel: %d is not in disabled state\n",
>> - mhi_chan->chan);
>> - goto error_init_chan;
>> - }
>> -
>> /* Check of client manages channel context for offload channels */
>> if (!mhi_chan->offload_ch) {
>> ret = mhi_init_chan_ctxt(mhi_cntrl, mhi_chan);
>> @@ -1274,34 +1320,11 @@ int mhi_prepare_channel(struct mhi_controller
>> *mhi_cntrl,
>> goto error_init_chan;
>> }
>>
>> - reinit_completion(&mhi_chan->completion);
>> - read_lock_bh(&mhi_cntrl->pm_lock);
>> - if (MHI_PM_IN_ERROR_STATE(mhi_cntrl->pm_state)) {
>> - read_unlock_bh(&mhi_cntrl->pm_lock);
>> - ret = -EIO;
>> - goto error_pm_state;
>> - }
>> -
>> - mhi_cntrl->wake_toggle(mhi_cntrl);
>> - read_unlock_bh(&mhi_cntrl->pm_lock);
>> - mhi_cntrl->runtime_get(mhi_cntrl);
>> - mhi_cntrl->runtime_put(mhi_cntrl);
>> -
>> - ret = mhi_send_cmd(mhi_cntrl, mhi_chan, MHI_CMD_START_CHAN);
>> + ret = mhi_update_channel_state(mhi_cntrl, mhi_chan,
>> + MHI_CH_STATE_TYPE_START);
>> if (ret)
>> goto error_pm_state;
>>
>> - ret = wait_for_completion_timeout(&mhi_chan->completion,
>> - msecs_to_jiffies(mhi_cntrl->timeout_ms));
>> - if (!ret || mhi_chan->ccs != MHI_EV_CC_SUCCESS) {
>> - ret = -EIO;
>> - goto error_pm_state;
>> - }
>> -
>> - write_lock_irq(&mhi_chan->lock);
>> - mhi_chan->ch_state = MHI_CH_STATE_ENABLED;
>> - write_unlock_irq(&mhi_chan->lock);
>> -
>> /* Pre-allocate buffer for xfer ring */
>> if (mhi_chan->pre_alloc) {
>> int nr_el = get_nr_avail_ring_elements(mhi_cntrl,
>> @@ -1339,9 +1362,6 @@ int mhi_prepare_channel(struct mhi_controller
>> *mhi_cntrl,
>>
>> mutex_unlock(&mhi_chan->mutex);
>>
>> - dev_dbg(dev, "Chan: %d successfully moved to start state\n",
>> - mhi_chan->chan);
>> -
>> return 0;
>>
>> error_pm_state:
>> --
>> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora
>> Forum,
>> a Linux Foundation Collaborative Project
>>

[1] https://lkml.org/lkml/2021/1/21/781

Thanks,
Bhaumik
---
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora
Forum,
a Linux Foundation Collaborative Project

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