linux-kernel - RE: [char-misc-next 6/6] mei: bus: add client dma interface

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Date:   Sun, 7 Feb 2021 14:03:11 +0000
From:   "Winkler, Tomas" <tomas.winkler@...el.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
CC:     "Usyskin, Alexander" <alexander.usyskin@...el.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "Grumbach, Emmanuel" <emmanuel.grumbach@...el.com>,
        "Coelho, Luciano" <luciano.coelho@...el.com>
Subject: RE: [char-misc-next 6/6] mei: bus: add client dma interface

> 
> On Sat, Feb 06, 2021 at 03:04:34PM +0000, Winkler, Tomas wrote:
> > > On Sat, Feb 06, 2021 at 04:43:25PM +0200, Tomas Winkler wrote:
> > > > From: Alexander Usyskin <alexander.usyskin@...el.com>
> > > >
> > > > Expose the client dma mapping via mei client bus interface.
> > > >
> > > > Signed-off-by: Alexander Usyskin <alexander.usyskin@...el.com>
> > > > Signed-off-by: Tomas Winkler <tomas.winkler@...el.com>
> > > > ---
> > > >  drivers/misc/mei/bus.c     | 46
> > > ++++++++++++++++++++++++++++++++++++++
> > > >  drivers/misc/mei/hw.h      |  5 +++++
> > > >  include/linux/mei_cl_bus.h |  3 +++
> > > >  3 files changed, 54 insertions(+)
> > > >
> > > > diff --git a/drivers/misc/mei/bus.c b/drivers/misc/mei/bus.c index
> > > > 34fb5e541fe5..d430710a5fe5 100644
> > > > --- a/drivers/misc/mei/bus.c
> > > > +++ b/drivers/misc/mei/bus.c
> > > > @@ -636,6 +636,52 @@ static void mei_cl_bus_vtag_free(struct
> > > mei_cl_device *cldev)
> > > >  	kfree(cl_vtag);
> > > >  }
> > > >
> > > > +void *mei_cldev_dma_map(struct mei_cl_device *cldev, u8
> > > > +buffer_id, size_t size) {
> > > > +	struct mei_device *bus;
> > > > +	struct mei_cl *cl;
> > > > +	int ret;
> > > > +
> > > > +	if (!cldev || !buffer_id || !size)
> > > > +		return ERR_PTR(-EINVAL);
> > > > +
> > > > +	if (!IS_ALIGNED(size, MEI_FW_PAGE_SIZE)) {
> > > > +		dev_err(&cldev->dev, "Map size should be aligned to %lu\n",
> > > > +			MEI_FW_PAGE_SIZE);
> > > > +		return ERR_PTR(-EINVAL);
> > > > +	}
> > > > +
> > > > +	cl = cldev->cl;
> > > > +	bus = cldev->bus;
> > > > +
> > > > +	mutex_lock(&bus->device_lock);
> > > > +	ret = mei_cl_dma_alloc_and_map(cl, NULL, buffer_id, size);
> > > > +	mutex_unlock(&bus->device_lock);
> > > > +	if (ret)
> > > > +		return ERR_PTR(ret);
> > > > +	return cl->dma.vaddr;
> > > > +}
> > > > +EXPORT_SYMBOL_GPL(mei_cldev_dma_map);
> > >
> > > Why are you exporting symbols without a user of them?
> > >
> > > That's a sure way to get them removed by someone right after this
> > > lands in the tree :)
> > >
> > > Please only add infrastructure for when you have a real user.
> > You are right,  the user is coming from wifi tree. We need merge before
> they do.
> > If you prefer we can merge that all from the wifi tree.
> 
> That wasn't documented well at all in your changelog comment :(
Note taken.  
> It can go through whatever tree needs it.
If possible please merge our changes already here, and let the wifi guys to finish their task in their tree, in their own time.
Thanks
Tomas