From: Albert ARIBAUD <albert.aribaud@free.fr>
To: u-boot@lists.denx.de
Subject: [U-Boot] [PATCH 0/4 V2] Add basic NVIDIA Tegra2 SoC support
Date: Sat, 15 Jan 2011 00:00:43 +0100 [thread overview]
Message-ID: <4D30D59B.3000102@free.fr> (raw)
In-Reply-To: <AANLkTikCQ_0cNFRj_5S2zShcJ-2qyvi24yeH0DcqEPf_@mail.gmail.com>
Hello,
Le 14/01/2011 23:39, Tom Warren a ?crit :
> So instead of, say uart->lcr = 0, you'd prefer writel(0, uart->lcr),
> where writel = __arch_putl(v, a) = (*(volatile unsigned int *)(a) =
> (v))?
> Is that different enough from 'uart->lcr = 0' to warrant the change?
> Does it add some HW barriers or forced read-before-write that the
> 'volatile' struct doesn't?
writel() and readl() do not introduce "read-before-write", that is, they
do not perform any more than what their names imply, but yes they do
introduce barriers, or more precisely, they force the compiler to do so.
Amicalement,
--
Albert.
next prev parent reply other threads:[~2011-01-14 23:00 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-01-14 17:11 [U-Boot] [PATCH 0/4 V2] Add basic NVIDIA Tegra2 SoC support Tom Warren
2011-01-14 17:11 ` [U-Boot] [PATCH 1/4 V2] arm: Tegra2: " Tom Warren
2011-01-14 17:11 ` [U-Boot] [PATCH 2/4 V2] serial: Add Tegra2 serial port support Tom Warren
2011-01-14 17:11 ` [U-Boot] [PATCH 3/4 V2] arm: Tegra2: Add support for NVIDIA Harmony board Tom Warren
2011-01-14 17:11 ` [U-Boot] [PATCH 4/4 V2] arm: Tegra2: Add support for NVIDIA Seaboard board Tom Warren
2011-01-14 19:59 ` [U-Boot] [PATCH 0/4 V2] Add basic NVIDIA Tegra2 SoC support Peter Tyser
2011-01-14 20:41 ` Tom Warren
2011-01-14 21:36 ` Peter Tyser
2011-01-14 22:39 ` Tom Warren
2011-01-14 23:00 ` Albert ARIBAUD [this message]
2011-01-14 23:23 ` Peter Tyser
2011-01-15 0:01 ` Wolfgang Denk
2011-01-17 23:27 ` Wolfgang Denk
2011-01-17 23:27 ` Wolfgang Denk
2011-01-19 21:23 ` Tom Warren
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