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Message-ID: <20210121144302.GA5473@work>
Date: Thu, 21 Jan 2021 20:13:02 +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,
loic.poulain@...aro.org
Subject: Re: [PATCH v5 3/9] bus: mhi: core: Improvements to the channel
handling state machine
On Fri, Jan 08, 2021 at 12:54:51PM -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.
>
> 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 | 166 +++++++++++++++++++++++-----------------
> 3 files changed, 114 insertions(+), 70 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 c22d7df..081fdf0 100644
> --- a/drivers/bus/mhi/core/main.c
> +++ b/drivers/bus/mhi/core/main.c
> @@ -1250,56 +1250,118 @@ 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;
> + enum mhi_cmd_type cmd = MHI_CMD_NOP;
> + int ret = -EIO;
> +
> + dev_dbg(dev, "Updating channel %s(%d) state to: %s\n", mhi_chan->name,
> + mhi_chan->chan, TO_CH_STATE_TYPE_STR(to_state));
Instead of explicitly using the channel name and its id, you should be
able to use `mhi_chan->mhi_dev->dev` so that dev_dbg() can provide that
information for you. For instance,
mhi0_IPCR: Updating channel state to RESET
Do it for all instances below.
> +
> + 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);
> + goto exit_invalid_state;
> + }
> + 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)
> + goto exit_invalid_state;
>
> - /* 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)
> + goto exit_invalid_state;
> +
> + cmd = MHI_CMD_START_CHAN;
> + break;
> + default:
> + goto exit_invalid_state;
> }
>
> - 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);
You are sneaking in a change here. Please add it to the commit description.
> + 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, "Failed to send %s(%d) %s command\n",
> + mhi_chan->name, mhi_chan->chan,
> + TO_CH_STATE_TYPE_STR(to_state));
> + goto exit_command_failure;
> }
>
> - 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, "Failed to receive %s(%d) %s command completion\n",
> + mhi_chan->name, mhi_chan->chan,
> + TO_CH_STATE_TYPE_STR(to_state));
> + ret = -EIO;
> + goto exit_command_failure;
> + }
>
> - 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, "Channel %s(%d) state change to %s successful\n",
> + mhi_chan->name, mhi_chan->chan, TO_CH_STATE_TYPE_STR(to_state));
> +
> +exit_command_failure:
> 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;
> +
This is not a recommended way to handle error paths. There should be a
single return for all error paths. Please fix it.
> +exit_invalid_state:
> + dev_err(dev, "Channel %s(%d) update to %s not allowed\n",
> + mhi_chan->name, mhi_chan->chan, TO_CH_STATE_TYPE_STR(to_state));
> +
> + return -EINVAL;
> +}
> +
> +static void __mhi_unprepare_channel(struct mhi_controller *mhi_cntrl,
> + struct mhi_chan *mhi_chan)
> +{
> + int ret;
> + struct device *dev = &mhi_cntrl->mhi_dev->dev;
> +
> + /* no more processing events for this channel */
Move this comment below.
Thanks,
Mani
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