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Message-ID: <20210331113515.GG15610@work>
Date: Wed, 31 Mar 2021 17:05:15 +0530
From: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
To: Bhaumik Bhatt <bbhatt@...eaurora.org>
Cc: linux-arm-msm@...r.kernel.org, hemantk@...eaurora.org,
jhugo@...eaurora.org, linux-kernel@...r.kernel.org,
carl.yin@...ctel.com, naveen.kumar@...ctel.com,
loic.poulain@...aro.org
Subject: Re: [PATCH v7 3/7] bus: mhi: core: Improvements to the channel
handling state machine
On Mon, Mar 29, 2021 at 07:11:43PM -0700, Bhaumik Bhatt wrote:
> Improve the channel handling state machine such that all commands
> go through a common function and a validation process to ensure
> that the state machine is not violated in any way and adheres to
> the MHI specification. Using this common function allows MHI to:
> 1. Fail early if device is in a bad state by attempting to assert
> device wake before sending a channel update command instead of
> performing a wake toggle and waiting longer for the send to fail
> 2. Use channel specific print messages to accurately identify the
> use client device for the channel(s) being updated
> 3. Eliminate unnecessary debug messages and code duplication
Please don't club these changes in a single patch. Split them as
individual patches.
Thanks,
Mani
>
> Signed-off-by: Bhaumik Bhatt <bbhatt@...eaurora.org>
> Reviewed-by: Hemant Kumar <hemantk@...eaurora.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 bd62efcb..64846c4 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 6f37439..d8fd197 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 0dc3749..6c3234e 100644
> --- a/drivers/bus/mhi/core/main.c
> +++ b/drivers/bus/mhi/core/main.c
> @@ -1208,56 +1208,114 @@ 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);
> }
>
> @@ -1265,28 +1323,16 @@ 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);
> @@ -1294,34 +1340,11 @@ 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,
> @@ -1359,9 +1382,6 @@ 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
>
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