linux-kernel - RE: [PATCH] mmc: disable UHS on broadcom sdhci

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Message-ID: <156984479488CD49A184F5CAB4AF93460709F237@IRVEXCHMB14.corp.ad.broadcom.com>
Date:	Mon, 18 Nov 2013 20:09:10 +0000
From:	"Stephen Hurd" <shurd@...adcom.com>
To:	"Olof Johansson" <olof@...om.net>,
	"Grant Grundler" <grundler@...omium.org>
cc:	"Chris Ball" <cjb@...top.org>,
	"linux-mmc@...r.kernel.org" <linux-mmc@...r.kernel.org>,
	"Olof Johansson" <olofj@...omium.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH] mmc: disable UHS on broadcom sdhci

> > SDHCI_QUIRK2_BCM57785_CR:
> >     Bit twiddles some Broadcom-specific registers and supresses an error
> >     about the 64k bar0.

> I think this can be done without spending a global SDHCI quirk bit. This
> is just a one-time setup that needs to be done, isn't it? It's hard
> to tell since there's no official errata described, but if it is, then
> overriding the probe function is the way to go instead, flipping these
> bits there and then call the regular probe.

My initial recollection is that this bit twiddling needs to be done any time the clock is touched, so it's not just one-time setup.  I'll ask the guys about it and get back to you.

The 64k bar0 suppression is just cosmetic, but I don't see anything in the public specs suggesting that there is a max limit on the size of the bar... not sure that it's appropriate to give a warning on it for *any* device, but it's absolutely incorrect for this device.


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