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

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Message-ID: <YB7EIciZrmBrEqUA@kroah.com>
Date:   Sat, 6 Feb 2021 17:30:25 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     "Winkler, Tomas" <tomas.winkler@...el.com>
Cc:     "Usyskin, Alexander" <alexander.usyskin@...el.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "Grumbach, Emmanuel" <emmanuel.grumbach@...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 :(

It can go through whatever tree needs it.

thanks,

greg k-h