From: Sascha Hauer <s.hauer@pengutronix.de>
To: Yann Sionneau <ysionneau@kalray.eu>
Cc: barebox@lists.infradead.org
Subject: Re: mci: SDHC generic driver? refactor dove-sdhci?
Date: Mon, 11 Feb 2019 09:48:11 +0100 [thread overview]
Message-ID: <20190211084811.eistdcv73tt5edxo@pengutronix.de> (raw)
In-Reply-To: <05f625c3-e8ab-157c-2c48-d82d5fc5953a@kalray.eu>
Hi Yann,
On Fri, Feb 08, 2019 at 04:49:09PM +0100, Yann Sionneau wrote:
> Hello,
>
> I've written a driver for snps,dw-mshc, which is compatible with SDHC spec.
Are you sure? "snps,dw-mshc" is not compatible to SDHCI and has a
separate driver in Linux. We also have this driver in barebox, not with
the "snps,dw-mshc" compatible, but with "altr,socfpga-dw-mshc". The
register layout looks quite different from SDHCI.
>
> Basically I've just copy pasted the dove-sdhci.c one and modified a few
> lines to add:
>
> * support for host_v4 mode
>
> * 64 bit addressing
>
> * 64-bit SDMA
>
> * PIO mode
>
> * Support for 10-bit clock divider (max divider of 2046 instead of 256)
>
> Chosing between SDMA and PIO is done with Kconfig defines at compile time.
> It's either one or the other.
>
> Since snps,dw-mshc and dove-sdhci share the same code, because both respect
> SDHC spec I would propose to rename dove-sdhci.c into sdhci.c and remove all
> dove mentions inside.
>
> Then write a dove-sdhci.c which registers via the sdhci generic layer and
> same thing for dw-mshc.
>
> This allows lot of code sharing between SDHC compatible devices and also
> eases a lot the writing of new drivers.
>
> Would that be OK?
We have several other SDHCI like drivers in barebox: bcm2835, tegra,
imx-esdhc. They are all slightly different and the Linux SDHCI driver is
a horrible thing. Instead of trying to write one driver for all of these
I'd rather suggest we keep our separate drivers and that we create a
common SHDCI file in which we add some library functions which we can
use from the more specific drivers.
Sascha
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prev parent reply other threads:[~2019-02-11 8:48 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-08 15:49 Yann Sionneau
2019-02-11 8:48 ` Sascha Hauer [this message]
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