Messages in this thread | | | Date | Thu, 03 Dec 2020 17:44:28 -0800 | From | Bhaumik Bhatt <> | Subject | Re: [PATCH v3 4/7] bus: mhi: core: Add support to stop or start channel data transfers |
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On 2020-12-02 04:33 PM, Hemant Kumar wrote: > Hi Bhaumik, > > On 12/2/20 3:40 PM, Bhaumik Bhatt wrote: >> Some MHI client drivers may want to request a pause or halt of >> data transfer activity on their channels. Support for this does >> not exist and must be introduced, wherein the channel context is >> not reset or cleared but only the STOP channel command is issued. >> This would need to be paired with an API that allows resuming the >> data transfer activity on channels by use of the START channel >> command. This API assumes that the context information is already > > is it a better option to make sure channel context is setup as this is > an exported API. Hence check for channel context bail out in case > channel context is not setup with an err msg ? > This is a better method, yes. Addressed in v4. >> setup. Enable this using two new APIs, mhi_start_transfer() and >> mhi_stop_transfer(). >> >> Signed-off-by: Bhaumik Bhatt <bbhatt@codeaurora.org> >> --- >> drivers/bus/mhi/core/main.c | 41 >> +++++++++++++++++++++++++++++++++++++++++ >> include/linux/mhi.h | 19 +++++++++++++++++++ >> 2 files changed, 60 insertions(+) >> >> diff --git a/drivers/bus/mhi/core/main.c b/drivers/bus/mhi/core/main.c >> index 4cc5ced..2e4b34a 100644 >> --- a/drivers/bus/mhi/core/main.c >> +++ b/drivers/bus/mhi/core/main.c >> @@ -1552,6 +1552,47 @@ void mhi_unprepare_from_transfer(struct >> mhi_device *mhi_dev) >> } >> EXPORT_SYMBOL_GPL(mhi_unprepare_from_transfer); >> +static int mhi_update_transfer_state(struct mhi_device *mhi_dev, >> + enum mhi_ch_state_type to_state) >> +{ >> + struct mhi_controller *mhi_cntrl = mhi_dev->mhi_cntrl; >> + struct mhi_chan *mhi_chan; >> + int dir, ret; >> + >> + for (dir = 0; dir < 2; dir++) { >> + mhi_chan = dir ? mhi_dev->ul_chan : mhi_dev->dl_chan; >> + >> + if (!mhi_chan) >> + continue; >> + >> + /* >> + * Bail out if one of the channels fail as client will reset >> + * both upon failure >> + */ >> + mutex_lock(&mhi_chan->mutex); >> + ret = mhi_update_channel_state(mhi_cntrl, mhi_chan, to_state); >> + if (ret) { >> + mutex_unlock(&mhi_chan->mutex); >> + return ret; >> + } >> + mutex_unlock(&mhi_chan->mutex); >> + } >> + >> + return 0; >> +} >> + >> +int mhi_stop_transfer(struct mhi_device *mhi_dev) >> +{ >> + return mhi_update_transfer_state(mhi_dev, MHI_CH_STATE_TYPE_STOP); >> +} >> +EXPORT_SYMBOL_GPL(mhi_stop_transfer); >> + >> +int mhi_start_transfer(struct mhi_device *mhi_dev) >> +{ >> + return mhi_update_transfer_state(mhi_dev, MHI_CH_STATE_TYPE_START); >> +} >> +EXPORT_SYMBOL_GPL(mhi_start_transfer); >> + >> int mhi_poll(struct mhi_device *mhi_dev, u32 budget) >> { >> struct mhi_controller *mhi_cntrl = mhi_dev->mhi_cntrl; >> diff --git a/include/linux/mhi.h b/include/linux/mhi.h >> index aa9757e..35779a0 100644 >> --- a/include/linux/mhi.h >> +++ b/include/linux/mhi.h >> @@ -704,6 +704,25 @@ int mhi_prepare_for_transfer(struct mhi_device >> *mhi_dev); >> void mhi_unprepare_from_transfer(struct mhi_device *mhi_dev); >> /** >> + * mhi_stop_transfer - Pauses ongoing channel activity by issuing the >> STOP >> + * channel command to both UL and DL channels. >> This command >> + * does not reset the channel context and the >> client drivers >> + * can issue mhi_start_transfer to resume >> activity. >> + * @mhi_dev: Device associated with the channels >> + */ >> +int mhi_stop_transfer(struct mhi_device *mhi_dev); >> + >> +/** >> + * mhi_start_transfer - Resumes channel activity by issuing the START >> channel >> + * command to both UL and DL channels. This >> command assumes >> + * the channel context is already setup and the >> client >> + * drivers can issue mhi_stop_transfer to pause >> activity if >> + * required. >> + * @mhi_dev: Device associated with the channels >> + */ >> +int mhi_start_transfer(struct mhi_device *mhi_dev); >> + >> +/** >> * mhi_poll - Poll for any available data in DL direction >> * @mhi_dev: Device associated with the channels >> * @budget: # of events to process >> > Overall change looks good. > > Thanks, > Hemant
Thanks, Bhaumik --- The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project
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