linux-kernel - Re: [PATCH 2/3] dmaengine: add wrapper functions for dmaengine

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Message-ID: <AANLkTi=tY=W05K5N77Xv6kz5CX9U2=Gvm2vDavMN5DSu@mail.gmail.com>
Date:	Fri, 24 Sep 2010 08:45:45 -0700
From:	Dan Williams <dan.j.williams@...el.com>
To:	Sascha Hauer <s.hauer@...gutronix.de>
Cc:	linux-kernel@...r.kernel.org,
	Linus Walleij <linus.ml.walleij@...il.com>,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 2/3] dmaengine: add wrapper functions for dmaengine

On Fri, Sep 24, 2010 at 12:25 AM, Sascha Hauer <s.hauer@...gutronix.de> wrote:
> Hi Dan,
>
> On Thu, Sep 23, 2010 at 12:53:58PM -0700, Dan Williams wrote:
>> > diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
>> > index 0df7864..635c60b 100644
>> > --- a/include/linux/dmaengine.h
>> > +++ b/include/linux/dmaengine.h
>> > @@ -491,6 +491,47 @@ struct dma_device {
>> >        void (*device_issue_pending)(struct dma_chan *chan);
>> >  };
>> >
>> > +static inline int dmaengine_device_control(struct dma_chan *chan,
>> > +                                          enum dma_ctrl_cmd cmd,
>> > +                                          unsigned long arg)
>> > +{
>> > +       return chan->device->device_control(chan, cmd, arg);
>> > +}
>> > +
>> > +static inline int dmaengine_slave_config(struct dma_chan *chan,
>> > +                                         struct dma_slave_config *config)
>> > +{
>> > +       return dmaengine_device_control(chan, DMA_SLAVE_CONFIG,
>> > +                       (unsigned long)config);
>> > +}
>> > +
>> > +static inline int dmaengine_terminate_all(struct dma_chan *chan)
>> > +{
>> > +       return dmaengine_device_control(chan, DMA_TERMINATE_ALL, 0);
>> > +}
>> > +
>> > +static inline struct dma_async_tx_descriptor *dmaengine_prep_slave_sg(
>> > +               struct dma_chan *chan, struct scatterlist *sgl,
>> > +               unsigned int sg_len, enum dma_data_direction direction,
>> > +               unsigned long flags)
>> > +{
>> > +       return chan->device->device_prep_slave_sg(chan, sgl, sg_len, direction,
>> > +                       flags);
>> > +}
>> > +
>> > +static inline struct dma_async_tx_descriptor *dmaengine_prep_cyclic(
>> > +               struct dma_chan *chan, dma_addr_t buf_addr, size_t buf_len,
>> > +               size_t period_len, enum dma_data_direction direction)
>> > +{
>> > +       return chan->device->device_prep_dma_cyclic(chan, buf_addr, buf_len,
>> > +                       period_len, direction);
>> > +}
>> > +
>>
>> No strong disagreements on the above, the type safety of
>> dmaengine_slave_config() is nice.
>
> So you have only small disagreements? ;) I can drop the dmaengine_prep_*
> functions and only keep the device_control functions if like it better.
>

The prep versions may just be code churn, unless there is another
advantage for having a helper... debug/tracing perhaps?

>>
>> > +static inline int dmaengine_tx_submit(struct dma_async_tx_descriptor *desc)
>> > +{
>> > +       return desc->tx_submit(desc);
>> > +}
>>
>> This one can drop the tx.
>
> You mean the function should be named dmaengine_submit?

Yes, the "tx" is often mistaken, understandably, for "transmit".
Linus proposed renaming ->tx_submit() to just ->submit().  This helper
would be a softer way to introduce that rename.

--
Dan
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