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Thu, 21 Jan 2021 06:43:05 -0800 (PST) Date: Thu, 21 Jan 2021 20:13:02 +0530 From: Manivannan Sadhasivam To: Bhaumik Bhatt Cc: linux-arm-msm@vger.kernel.org, hemantk@codeaurora.org, jhugo@codeaurora.org, linux-kernel@vger.kernel.org, loic.poulain@linaro.org Subject: Re: [PATCH v5 3/9] bus: mhi: core: Improvements to the channel handling state machine Message-ID: <20210121144302.GA5473@work> References: <1610139297-36435-1-git-send-email-bbhatt@codeaurora.org> <1610139297-36435-4-git-send-email-bbhatt@codeaurora.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1610139297-36435-4-git-send-email-bbhatt@codeaurora.org> User-Agent: Mutt/1.9.4 (2018-02-28) Precedence: bulk List-ID: X-Mailing-List: linux-arm-msm@vger.kernel.org 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 > Reviewed-by: Hemant Kumar > --- > 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