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From: Arnd Bergmann <arnd@arndb.de>
To: Sinan Kaya <okaya@codeaurora.org>
Cc: Timur Tabi <timur@codeaurora.org>,
	sulrich@codeaurora.org, linux-arm-msm@vger.kernel.org,
	Linux ARM <linux-arm-kernel@lists.infradead.org>,
	linux-arch <linux-arch@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v3 1/5] io: define several IO & PIO barrier types for the asm-generic version
Date: Thu, 5 Apr 2018 09:00:08 +0200	[thread overview]
Message-ID: <CAK8P3a0Noun+8AaRUcMdOX09KXxFXZxfcyUgJnezPkS2gVkg6w@mail.gmail.com> (raw)
In-Reply-To: <1522886301-25955-1-git-send-email-okaya@codeaurora.org>

On Thu, Apr 5, 2018 at 1:58 AM, Sinan Kaya <okaya@codeaurora.org> wrote:

Looks good, but I'd change the comments to ones that document exactly
what those barriers are for:

> +#ifndef __io_ar
> +#ifdef rmb
> +/* prefer rmb() as the default implementation of __io_ar() if supported */
> +#define __io_ar()      rmb()

/*
 * prevent prefetching of coherent DMA data ahead of a dma-complete */

> +#ifndef __io_bw
> +#ifdef wmb
> +/* prefer wmb() as the default implementation of __io_bw() if supported */
> +#define __io_bw()      wmb()
> +#else

/* flush writes to coherent DMA data before possibly triggering a DMA read */

> +#ifndef __io_aw
> +#define __io_aw()      barrier()
> +#endif

/* serialize device access against a spin_unlock, usually handled there */

The other four patches look perfect already.  What's the timing we need for
these patches? Are they 4.18 material, or do we need them in 4.17 and
stable kernels to work around known bugs?

      Arnd

WARNING: multiple messages have this Message-ID (diff)
From: arnd@arndb.de (Arnd Bergmann)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v3 1/5] io: define several IO & PIO barrier types for the asm-generic version
Date: Thu, 5 Apr 2018 09:00:08 +0200	[thread overview]
Message-ID: <CAK8P3a0Noun+8AaRUcMdOX09KXxFXZxfcyUgJnezPkS2gVkg6w@mail.gmail.com> (raw)
In-Reply-To: <1522886301-25955-1-git-send-email-okaya@codeaurora.org>

On Thu, Apr 5, 2018 at 1:58 AM, Sinan Kaya <okaya@codeaurora.org> wrote:

Looks good, but I'd change the comments to ones that document exactly
what those barriers are for:

> +#ifndef __io_ar
> +#ifdef rmb
> +/* prefer rmb() as the default implementation of __io_ar() if supported */
> +#define __io_ar()      rmb()

/*
 * prevent prefetching of coherent DMA data ahead of a dma-complete */

> +#ifndef __io_bw
> +#ifdef wmb
> +/* prefer wmb() as the default implementation of __io_bw() if supported */
> +#define __io_bw()      wmb()
> +#else

/* flush writes to coherent DMA data before possibly triggering a DMA read */

> +#ifndef __io_aw
> +#define __io_aw()      barrier()
> +#endif

/* serialize device access against a spin_unlock, usually handled there */

The other four patches look perfect already.  What's the timing we need for
these patches? Are they 4.18 material, or do we need them in 4.17 and
stable kernels to work around known bugs?

      Arnd

  parent reply	other threads:[~2018-04-05  7:00 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-04 23:58 [PATCH v3 1/5] io: define several IO & PIO barrier types for the asm-generic version Sinan Kaya
2018-04-04 23:58 ` Sinan Kaya
2018-04-04 23:58 ` [PATCH v3 2/5] io: define stronger ordering for the default readX() implementation Sinan Kaya
2018-04-04 23:58   ` Sinan Kaya
2018-04-04 23:58   ` Sinan Kaya
2018-04-04 23:58 ` [PATCH v3 3/5] io: define stronger ordering for the default writeX() implementation Sinan Kaya
2018-04-04 23:58   ` Sinan Kaya
2018-04-04 23:58 ` [PATCH v3 4/5] io: change outX() to have their own IO barrier overrides Sinan Kaya
2018-04-04 23:58   ` Sinan Kaya
2018-04-04 23:58 ` [PATCH v3 5/5] io: change inX() " Sinan Kaya
2018-04-04 23:58   ` Sinan Kaya
2018-04-05  7:00 ` Arnd Bergmann [this message]
2018-04-05  7:00   ` [PATCH v3 1/5] io: define several IO & PIO barrier types for the asm-generic version Arnd Bergmann
2018-04-05 11:48   ` okaya
2018-04-05 11:48     ` okaya at codeaurora.org
2018-04-05 11:58     ` Arnd Bergmann
2018-04-05 11:58       ` Arnd Bergmann

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