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Groups > linux.kernel > #1643003
| From | Dong Aisheng <dongas86@gmail.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [V2, 2/6] tty: serial: lpuart: add little endian 32 bit register support |
| Date | 2017-05-17 08:20 +0200 |
| Message-ID | <tI0tr-7Un-1@gated-at.bofh.it> (permalink) |
| References | (1 earlier) <tHIGf-4Ub-17@gated-at.bofh.it> <tHXYC-6cB-5@gated-at.bofh.it> <tHZQJ-7s4-3@gated-at.bofh.it> <tI00p-7v7-23@gated-at.bofh.it> <tI0a6-7yt-3@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On Wed, May 17, 2017 at 08:50:39AM +0300, Nikita Yushchenko wrote:
> >>>>> static u32 lpuart32_read(void __iomem *addr)
> >>>>> {
> >>>>> - return ioread32be(addr);
> >>>>> + return lpuart_is_be ? ioread32be(addr) : readl(addr);
> >>>>> }
> >>>>>
> >>>>> static void lpuart32_write(u32 val, void __iomem *addr)
> >>>>> {
> >>>>> - iowrite32be(val, addr);
> >>>>> + if (lpuart_is_be)
> >>>>> + iowrite32be(val, addr);
> >>>>> + else
> >>>>> + writel(val, addr);
> >>>>> }
> >>>>
> >>>> What if this is ever executed on big endian system?
> >>>>
> >>>
> >>> Sorry, not catching the point...
> >>>
> >>> What issues will meet?
> >>
> >> Isn't writel() in host endian?
> >
> > On big endian systems, it is supposed to run iowrite32be.
>
> Your code states, "force BE if lpuart_is_be, don't care otherwise".
> This semantics looks questionable for code reviewer.
> If driver handles endian, should't it be explicit in both cases?
> And if indeed driver means handling BE explicitly, but don't caring
> otherwise, maybe variable name should suggest that (i.e. "force_be")?
>
For lpuart32, only two cases that LS platforms is Big endian while
IMX is little endian.
It's SoC IP native property, i don't think force_be is better.
Regards
Dong Aisheng
> Although driver maintainer could think differently. I won't insist on this.
>
> Nikita
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Re: [V2, 2/6] tty: serial: lpuart: add little endian 32 bit register support Nikita Yushchenko <nikita.yoush@cogentembedded.com> - 2017-05-16 13:20 +0200
Re: [V2, 2/6] tty: serial: lpuart: add little endian 32 bit register support Dong Aisheng <dongas86@gmail.com> - 2017-05-17 05:40 +0200
Re: [V2, 2/6] tty: serial: lpuart: add little endian 32 bit register support Nikita Yushchenko <nikita.yoush@cogentembedded.com> - 2017-05-17 07:40 +0200
Re: [V2, 2/6] tty: serial: lpuart: add little endian 32 bit register support Dong Aisheng <dongas86@gmail.com> - 2017-05-17 07:50 +0200
Re: [V2, 2/6] tty: serial: lpuart: add little endian 32 bit register support Nikita Yushchenko <nikita.yoush@cogentembedded.com> - 2017-05-17 08:00 +0200
Re: [V2, 2/6] tty: serial: lpuart: add little endian 32 bit register support Dong Aisheng <dongas86@gmail.com> - 2017-05-17 08:20 +0200
Re: [V2, 2/6] tty: serial: lpuart: add little endian 32 bit register support Andy Shevchenko <andy.shevchenko@gmail.com> - 2017-05-17 12:00 +0200
Re: [V2, 2/6] tty: serial: lpuart: add little endian 32 bit register support Andy Shevchenko <andy.shevchenko@gmail.com> - 2017-05-17 12:00 +0200
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