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Message-ID: <ad8da5472b9e62dc4ca695c9cb58d2c735ce1594.camel@microchip.com>
Date: Tue, 16 May 2023 05:20:36 +0000
From: <Kelvin.Cao@...rochip.com>
To: <hch@...radead.org>
CC: <dmaengine@...r.kernel.org>, <vkoul@...nel.org>,
<George.Ge@...rochip.com>, <linux-kernel@...r.kernel.org>,
<logang@...tatee.com>, <tglx@...utronix.de>,
<christophe.jaillet@...adoo.fr>
Subject: Re: [PATCH v4 1/1] dmaengine: switchtec-dma: Introduce Switchtec DMA
engine PCI driver
On Mon, 2023-05-15 at 22:00 -0700, Christoph Hellwig wrote:
> EXTERNAL EMAIL: Do not click links or open attachments unless you
> know the content is safe
>
> On Mon, May 15, 2023 at 06:18:07PM +0000,
> Kelvin.Cao@...rochip.com wrote:
> > > I find this rather confusing, especially as some code literally
> > > switches on the op to fill in either set.
> >
> > It's a hardware interface, and not possible to change it at the
> > point.
> > I guess I can make it look slightly better by grouping the related
> > names together:
> >
> > union {
> > struct {
> > __le32 saddr_lo;
> > __le32 saddr_hi;
> > };
> > struct {
> > __le32 widata_lo;
> > __le32 widata_hi;
> > };
> > };
>
> The hardware interface is simply:
>
> __le32 field_lo;
> __le32 field_hi;
>
> hardware documentation might decide to give those fields two
> different
> names just to confuse you :)
>
> I think everyone else would be served better by:
>
> __le32 addr_lo; /* SADDR_LO/WIADDR_LO */
> __le32 addr_hi; /* SADDR_HI/WIADDR_HI */
>
It's simple and clean, thanks!
Kelvin
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