[PATCH] bus: mhi: Add inbound buffers allocation flag

[PATCH] bus: mhi: Add inbound buffers allocation flag

[Loic Poulain]

Currently, the MHI controller driver defines which channels should
have their inbound buffers allocated and queued. But ideally, this is
something that should be decided by the MHI device driver instead,
which actually deals with that buffers.

Add a flag parameter to mhi_prepare_for_transfer allowing to specify
if buffers have to be allocated and queued by the MHI stack.

Keep auto_queue flag for now, but should be removed at some point.

Signed-off-by: Loic Poulain <loic.poulain@linaro.org>
---
 drivers/bus/mhi/core/internal.h |  2 +-
 drivers/bus/mhi/core/main.c     | 11 ++++++++---
 drivers/net/mhi_net.c           |  2 +-
 include/linux/mhi.h             | 12 +++++++++++-
 net/qrtr/mhi.c                  |  2 +-
 5 files changed, 22 insertions(+), 7 deletions(-)

diff --git a/drivers/bus/mhi/core/internal.h b/drivers/bus/mhi/core/internal.h
index 6f80ec3..7512602 100644
--- a/drivers/bus/mhi/core/internal.h
+++ b/drivers/bus/mhi/core/internal.h
@@ -664,7 +664,7 @@ void mhi_rddm_prepare(struct mhi_controller *mhi_cntrl,
 		      struct image_info *img_info);
 void mhi_fw_load_handler(struct mhi_controller *mhi_cntrl);
 int mhi_prepare_channel(struct mhi_controller *mhi_cntrl,
-			struct mhi_chan *mhi_chan);
+			struct mhi_chan *mhi_chan, enum mhi_chan_flags flags);
 int mhi_init_chan_ctxt(struct mhi_controller *mhi_cntrl,
 		       struct mhi_chan *mhi_chan);
 void mhi_deinit_chan_ctxt(struct mhi_controller *mhi_cntrl,
diff --git a/drivers/bus/mhi/core/main.c b/drivers/bus/mhi/core/main.c
index 9b42540..6b6ad6b 100644
--- a/drivers/bus/mhi/core/main.c
+++ b/drivers/bus/mhi/core/main.c
@@ -1292,7 +1292,8 @@ static void __mhi_unprepare_channel(struct mhi_controller *mhi_cntrl,
 }
 
 int mhi_prepare_channel(struct mhi_controller *mhi_cntrl,
-			struct mhi_chan *mhi_chan)
+			struct mhi_chan *mhi_chan,
+			enum mhi_chan_flags flags)
 {
 	int ret = 0;
 	struct device *dev = &mhi_cntrl->mhi_dev->dev;
@@ -1352,6 +1353,9 @@ int mhi_prepare_channel(struct mhi_controller *mhi_cntrl,
 	mhi_chan->ch_state = MHI_CH_STATE_ENABLED;
 	write_unlock_irq(&mhi_chan->lock);
 
+	if (mhi_chan->dir == DMA_FROM_DEVICE)
+		mhi_chan->pre_alloc = !!(flags & MHI_CH_INBOUND_ALLOC_BUFS);
+
 	/* Pre-allocate buffer for xfer ring */
 	if (mhi_chan->pre_alloc) {
 		int nr_el = get_nr_avail_ring_elements(mhi_cntrl,
@@ -1498,7 +1502,8 @@ void mhi_reset_chan(struct mhi_controller *mhi_cntrl, struct mhi_chan *mhi_chan)
 }
 
 /* Move channel to start state */
-int mhi_prepare_for_transfer(struct mhi_device *mhi_dev)
+int mhi_prepare_for_transfer(struct mhi_device *mhi_dev,
+			     enum mhi_chan_flags flags)
 {
 	int ret, dir;
 	struct mhi_controller *mhi_cntrl = mhi_dev->mhi_cntrl;
@@ -1509,7 +1514,7 @@ int mhi_prepare_for_transfer(struct mhi_device *mhi_dev)
 		if (!mhi_chan)
 			continue;
 
-		ret = mhi_prepare_channel(mhi_cntrl, mhi_chan);
+		ret = mhi_prepare_channel(mhi_cntrl, mhi_chan, flags);
 		if (ret)
 			goto error_open_chan;
 	}
diff --git a/drivers/net/mhi_net.c b/drivers/net/mhi_net.c
index fa41d8c..b7f7f2e 100644
--- a/drivers/net/mhi_net.c
+++ b/drivers/net/mhi_net.c
@@ -265,7 +265,7 @@ static int mhi_net_probe(struct mhi_device *mhi_dev,
 	u64_stats_init(&mhi_netdev->stats.tx_syncp);
 
 	/* Start MHI channels */
-	err = mhi_prepare_for_transfer(mhi_dev);
+	err = mhi_prepare_for_transfer(mhi_dev, 0);
 	if (err)
 		goto out_err;
 
diff --git a/include/linux/mhi.h b/include/linux/mhi.h
index 209b335..6723339 100644
--- a/include/linux/mhi.h
+++ b/include/linux/mhi.h
@@ -60,6 +60,14 @@ enum mhi_flags {
 };
 
 /**
+ * enum mhi_chan_flags - MHI channel flags
+ * @MHI_CH_INBOUND_ALLOC_BUFS: Automatically allocate and queue inbound buffers
+ */
+enum mhi_chan_flags {
+	MHI_CH_INBOUND_ALLOC_BUFS = BIT(0),
+};
+
+/**
  * enum mhi_device_type - Device types
  * @MHI_DEVICE_XFER: Handles data transfer
  * @MHI_DEVICE_CONTROLLER: Control device
@@ -705,8 +713,10 @@ void mhi_device_put(struct mhi_device *mhi_dev);
 /**
  * mhi_prepare_for_transfer - Setup channel for data transfer
  * @mhi_dev: Device associated with the channels
+ * @flags: MHI channel flags
  */
-int mhi_prepare_for_transfer(struct mhi_device *mhi_dev);
+int mhi_prepare_for_transfer(struct mhi_device *mhi_dev,
+			     enum mhi_chan_flags flags);
 
 /**
  * mhi_unprepare_from_transfer - Unprepare the channels
diff --git a/net/qrtr/mhi.c b/net/qrtr/mhi.c
index 2bf2b19..47afded 100644
--- a/net/qrtr/mhi.c
+++ b/net/qrtr/mhi.c
@@ -77,7 +77,7 @@ static int qcom_mhi_qrtr_probe(struct mhi_device *mhi_dev,
 	int rc;
 
 	/* start channels */
-	rc = mhi_prepare_for_transfer(mhi_dev);
+	rc = mhi_prepare_for_transfer(mhi_dev, MHI_CH_INBOUND_ALLOC_BUFS);
 	if (rc)
 		return rc;
 
-- 
2.7.4

Re: [PATCH] bus: mhi: Add inbound buffers allocation flag

[Manivannan Sadhasivam]

On Wed, Jan 06, 2021 at 02:43:43PM +0100, Loic Poulain wrote:
> Currently, the MHI controller driver defines which channels should
> have their inbound buffers allocated and queued. But ideally, this is
> something that should be decided by the MHI device driver instead,

We call them, "MHI client drivers"

> which actually deals with that buffers.
> 
> Add a flag parameter to mhi_prepare_for_transfer allowing to specify
> if buffers have to be allocated and queued by the MHI stack.
> 
> Keep auto_queue flag for now, but should be removed at some point.
> 
> Signed-off-by: Loic Poulain <loic.poulain@linaro.org>
> ---
>  drivers/bus/mhi/core/internal.h |  2 +-
>  drivers/bus/mhi/core/main.c     | 11 ++++++++---
>  drivers/net/mhi_net.c           |  2 +-
>  include/linux/mhi.h             | 12 +++++++++++-
>  net/qrtr/mhi.c                  |  2 +-
>  5 files changed, 22 insertions(+), 7 deletions(-)
> 

[...]

> diff --git a/drivers/net/mhi_net.c b/drivers/net/mhi_net.c
> index fa41d8c..b7f7f2e 100644
> --- a/drivers/net/mhi_net.c
> +++ b/drivers/net/mhi_net.c
> @@ -265,7 +265,7 @@ static int mhi_net_probe(struct mhi_device *mhi_dev,
>  	u64_stats_init(&mhi_netdev->stats.tx_syncp);
>  
>  	/* Start MHI channels */
> -	err = mhi_prepare_for_transfer(mhi_dev);
> +	err = mhi_prepare_for_transfer(mhi_dev, 0);

Eventhough I'd like Hemant to comment on this patch, AFAIU this looks to
me a controller dependent behaviour. The controller should have the
information whether a particular channel can auto queue or not then the
client driver can be agnostic.

>  	if (err)
>  		goto out_err;
>  
> diff --git a/include/linux/mhi.h b/include/linux/mhi.h
> index 209b335..6723339 100644
> --- a/include/linux/mhi.h
> +++ b/include/linux/mhi.h
> @@ -60,6 +60,14 @@ enum mhi_flags {
>  };
>  
>  /**
> + * enum mhi_chan_flags - MHI channel flags
> + * @MHI_CH_INBOUND_ALLOC_BUFS: Automatically allocate and queue inbound buffers
> + */
> +enum mhi_chan_flags {
> +	MHI_CH_INBOUND_ALLOC_BUFS = BIT(0),
> +};
> +
> +/**
>   * enum mhi_device_type - Device types
>   * @MHI_DEVICE_XFER: Handles data transfer
>   * @MHI_DEVICE_CONTROLLER: Control device
> @@ -705,8 +713,10 @@ void mhi_device_put(struct mhi_device *mhi_dev);
>  /**
>   * mhi_prepare_for_transfer - Setup channel for data transfer
>   * @mhi_dev: Device associated with the channels
> + * @flags: MHI channel flags
>   */
> -int mhi_prepare_for_transfer(struct mhi_device *mhi_dev);
> +int mhi_prepare_for_transfer(struct mhi_device *mhi_dev,
> +			     enum mhi_chan_flags flags);
>  
>  /**
>   * mhi_unprepare_from_transfer - Unprepare the channels
> diff --git a/net/qrtr/mhi.c b/net/qrtr/mhi.c
> index 2bf2b19..47afded 100644
> --- a/net/qrtr/mhi.c
> +++ b/net/qrtr/mhi.c
> @@ -77,7 +77,7 @@ static int qcom_mhi_qrtr_probe(struct mhi_device *mhi_dev,
>  	int rc;
>  
>  	/* start channels */
> -	rc = mhi_prepare_for_transfer(mhi_dev);
> +	rc = mhi_prepare_for_transfer(mhi_dev, MHI_CH_INBOUND_ALLOC_BUFS);

Are you sure it requires auto queued channel?

Thanks,
Mani

>  	if (rc)
>  		return rc;
>  
> -- 
> 2.7.4
> 

Re: [PATCH] bus: mhi: Add inbound buffers allocation flag

[Manivannan Sadhasivam]

On Fri, Jan 08, 2021 at 03:01:59PM +0100, Loic Poulain wrote:
> Hi Mani,
> 
> On Fri, 8 Jan 2021 at 14:44, Manivannan Sadhasivam <
> manivannan.sadhasivam@linaro.org> wrote:
> 
> > On Wed, Jan 06, 2021 at 02:43:43PM +0100, Loic Poulain wrote:
> > > Currently, the MHI controller driver defines which channels should
> > > have their inbound buffers allocated and queued. But ideally, this is
> > > something that should be decided by the MHI device driver instead,
> >
> > We call them, "MHI client drivers"
> >
> 
> I'll fix that.
> 
> 
> > > which actually deals with that buffers.
> > >
> > > Add a flag parameter to mhi_prepare_for_transfer allowing to specify
> > > if buffers have to be allocated and queued by the MHI stack.
> > >
> > > Keep auto_queue flag for now, but should be removed at some point.
> > >
> > > Signed-off-by: Loic Poulain <loic.poulain@linaro.org>
> > > ---
> > >  drivers/bus/mhi/core/internal.h |  2 +-
> > >  drivers/bus/mhi/core/main.c     | 11 ++++++++---
> > >  drivers/net/mhi_net.c           |  2 +-
> > >  include/linux/mhi.h             | 12 +++++++++++-
> > >  net/qrtr/mhi.c                  |  2 +-
> > >  5 files changed, 22 insertions(+), 7 deletions(-)
> > >
> >
> > [...]
> >
> > > diff --git a/drivers/net/mhi_net.c b/drivers/net/mhi_net.c
> > > index fa41d8c..b7f7f2e 100644
> > > --- a/drivers/net/mhi_net.c
> > > +++ b/drivers/net/mhi_net.c
> > > @@ -265,7 +265,7 @@ static int mhi_net_probe(struct mhi_device *mhi_dev,
> > >       u64_stats_init(&mhi_netdev->stats.tx_syncp);
> > >
> > >       /* Start MHI channels */
> > > -     err = mhi_prepare_for_transfer(mhi_dev);
> > > +     err = mhi_prepare_for_transfer(mhi_dev, 0);
> >
> > Eventhough I'd like Hemant to comment on this patch, AFAIU this looks to
> > me a controller dependent behaviour. The controller should have the
> > information whether a particular channel can auto queue or not then the
> > client driver can be agnostic.
> >
> 
> The client driver can not be agnostic if this information is defined on the
> controller side. In one case client driver needs to allocate (and queue)
> its own buffers and in the other case it uses the pre-allocated ones.
> Moreover, that will break compatibility if we have one controller (e.g. a
> Wifi MHI controller) that e.g. defines IPCR channels as pre-allocated and
> another one that defines IPCR channels as non-pre-allocated. Having
> pre-allocated channels is not something related to the MHI device but to
> how the host (client driver) wants to manage buffers. It would then make
> sense to let this choice to the client driver.
> 
> 
> >
> > >       if (err)
> > >               goto out_err;
> > >
> > > diff --git a/include/linux/mhi.h b/include/linux/mhi.h
> > > index 209b335..6723339 100644
> > > --- a/include/linux/mhi.h
> > > +++ b/include/linux/mhi.h
> > > @@ -60,6 +60,14 @@ enum mhi_flags {
> > >  };
> > >
> > >  /**
> > > + * enum mhi_chan_flags - MHI channel flags
> > > + * @MHI_CH_INBOUND_ALLOC_BUFS: Automatically allocate and queue inbound
> > buffers
> > > + */
> > > +enum mhi_chan_flags {
> > > +     MHI_CH_INBOUND_ALLOC_BUFS = BIT(0),
> > > +};
> > > +
> > > +/**
> > >   * enum mhi_device_type - Device types
> > >   * @MHI_DEVICE_XFER: Handles data transfer
> > >   * @MHI_DEVICE_CONTROLLER: Control device
> > > @@ -705,8 +713,10 @@ void mhi_device_put(struct mhi_device *mhi_dev);
> > >  /**
> > >   * mhi_prepare_for_transfer - Setup channel for data transfer
> > >   * @mhi_dev: Device associated with the channels
> > > + * @flags: MHI channel flags
> > >   */
> > > -int mhi_prepare_for_transfer(struct mhi_device *mhi_dev);
> > > +int mhi_prepare_for_transfer(struct mhi_device *mhi_dev,
> > > +                          enum mhi_chan_flags flags);
> > >
> > >  /**
> > >   * mhi_unprepare_from_transfer - Unprepare the channels
> > > diff --git a/net/qrtr/mhi.c b/net/qrtr/mhi.c
> > > index 2bf2b19..47afded 100644
> > > --- a/net/qrtr/mhi.c
> > > +++ b/net/qrtr/mhi.c
> > > @@ -77,7 +77,7 @@ static int qcom_mhi_qrtr_probe(struct mhi_device
> > *mhi_dev,
> > >       int rc;
> > >
> > >       /* start channels */
> > > -     rc = mhi_prepare_for_transfer(mhi_dev);
> > > +     rc = mhi_prepare_for_transfer(mhi_dev, MHI_CH_INBOUND_ALLOC_BUFS);
> >
> > Are you sure it requires auto queued channel?
> >
> 
> This is how mhi-qrtr has been implemented, yes.
> 

skb is allocated in qrtr_endpoint_post(). Then how the host can pre
allocate the buffer here? Am I missing something?

Thanks,
Mani

> Regards,
> Loic

Re: [PATCH] bus: mhi: Add inbound buffers allocation flag

[Manivannan Sadhasivam]

On Fri, Jan 08, 2021 at 04:46:49PM +0100, Loic Poulain wrote:
> Hi Mani,
> 
> On Fri, 8 Jan 2021 at 16:30, Manivannan Sadhasivam <
> manivannan.sadhasivam@linaro.org> wrote:
> 
> > > > >       /* start channels */
> > > > > -     rc = mhi_prepare_for_transfer(mhi_dev);
> > > > > +     rc = mhi_prepare_for_transfer(mhi_dev,
> > MHI_CH_INBOUND_ALLOC_BUFS);
> > > >
> > > > Are you sure it requires auto queued channel?
> > > >
> > >
> > > This is how mhi-qrtr has been implemented, yes.
> > >
> >
> > skb is allocated in qrtr_endpoint_post(). Then how the host can pre
> > allocate the buffer here? Am I missing something?
> >
> 
> The initial MHI buffer is pre-allocated by the MHI core, so that mhi-qrtr
> only has to register a dl_callback without having to allocate and queue its
> own buffers. On dl_callback mhi-qrtr calls qrtr_endpoint_post(data) which
> allocates an skb and copy the MHI buffer (data) into that skb. When
> mhi-qrtr dl_callback finishes, the MHI buffer is re-queued automatically by
> the MHI core.
> 

Oops... My bad! There is the "auto_queue" for dl chan. Sorry for the noise.

Thanks,
Mani

> Regards,
> Loic
> 
> 
> >
> > Thanks,
> > Mani
> >
> > > Regards,
> > > Loic
> >

Re: [PATCH] bus: mhi: Add inbound buffers allocation flag

[Hemant Kumar]

On 1/8/21 7:30 AM, Manivannan Sadhasivam wrote:
> On Fri, Jan 08, 2021 at 03:01:59PM +0100, Loic Poulain wrote:
>> Hi Mani,
>>
>> On Fri, 8 Jan 2021 at 14:44, Manivannan Sadhasivam <
>> manivannan.sadhasivam@linaro.org> wrote:
>>
>>> On Wed, Jan 06, 2021 at 02:43:43PM +0100, Loic Poulain wrote:
>>>> Currently, the MHI controller driver defines which channels should
>>>> have their inbound buffers allocated and queued. But ideally, this is
>>>> something that should be decided by the MHI device driver instead,
>>>
>>> We call them, "MHI client drivers"
>>>
>>
>> I'll fix that.
>>
>>
>>>> which actually deals with that buffers.
>>>>
>>>> Add a flag parameter to mhi_prepare_for_transfer allowing to specify
>>>> if buffers have to be allocated and queued by the MHI stack.
>>>>
>>>> Keep auto_queue flag for now, but should be removed at some point.
>>>>
>>>> Signed-off-by: Loic Poulain <loic.poulain@linaro.org>
>>>> ---
>>>>   drivers/bus/mhi/core/internal.h |  2 +-
>>>>   drivers/bus/mhi/core/main.c     | 11 ++++++++---
>>>>   drivers/net/mhi_net.c           |  2 +-
>>>>   include/linux/mhi.h             | 12 +++++++++++-
>>>>   net/qrtr/mhi.c                  |  2 +-
>>>>   5 files changed, 22 insertions(+), 7 deletions(-)
>>>>
>>>
>>> [...]
>>>
>>>> diff --git a/drivers/net/mhi_net.c b/drivers/net/mhi_net.c
>>>> index fa41d8c..b7f7f2e 100644
>>>> --- a/drivers/net/mhi_net.c
>>>> +++ b/drivers/net/mhi_net.c
>>>> @@ -265,7 +265,7 @@ static int mhi_net_probe(struct mhi_device *mhi_dev,
>>>>        u64_stats_init(&mhi_netdev->stats.tx_syncp);
>>>>
>>>>        /* Start MHI channels */
>>>> -     err = mhi_prepare_for_transfer(mhi_dev);
>>>> +     err = mhi_prepare_for_transfer(mhi_dev, 0);
>>>
>>> Eventhough I'd like Hemant to comment on this patch, AFAIU this looks to
>>> me a controller dependent behaviour. The controller should have the
>>> information whether a particular channel can auto queue or not then the
>>> client driver can be agnostic.

I am fine with his change, and agree that MHI client driver should be 
able to make the decision.
Having said that, can we merge this on top of UCI :).
[..]

Thanks,
Hemant
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