From: andrew@lunn.ch (Andrew Lunn)
Date: Tue, 6 Mar 2012 18:53:33 +0100
Subject: [RFC 00/14] Generic clk for Orion platforms.
In-Reply-To: <20120306172341.GU5050@titan.lakedaemon.net>
References: <1331015471-28872-1-git-send-email-andrew@lunn.ch>
 <20120306155840.GS5050@titan.lakedaemon.net>
 <20120306161743.GI24858@lunn.ch>
 <20120306172341.GU5050@titan.lakedaemon.net>
Message-ID: <20120306175333.GA16608@lunn.ch>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

> > You missed an important point. No driver has claimed these, but u-boot
> > has turned them on.
> 
> This sounds like a bug in u-boot.

Is it? Even if it is, we have to live with it. Otherwise we introduce
a regression, which is a big no-no. Also, how many users know how to
upgrade u-boot? I don't have the necessary JTAG setup for my boxes, so
i'm not going to risk bricking them by trying to upgrade u-boot.

> Until that happens, could we walk across kirkwood_clks[] in
> kirkwood_clock_gate() to determine what is in use?  eg:
> 
> #########
> curr = readl(CLOCK_GATING_CTRL);
> ...
> used = CGC_DUNIT | CGC_RESERVED;
> 
> for (i = 0; i < ARRAY_SIZE(kirkwood_clks); i++) {
> 	if (kirkwood_clks[i]->enable_count)
> 		used |= kirkwood_clks[i]->/*PFM*/->mask;
> }
> 
> /* disable anything in curr, but not in used */
> if (CGC_SATA0 & (curr & ~used)) {
> 	/* disable sata0 logic */
> }
> 
> ...
> #########

NO! clk is opaque. You should not be accessing members inside it. The
clk struct members are not even declared when using the normal include
files.

Probably the short term solution is to simply add a deliberate
regression, and not turn them off. Then help Mike implement generic
code to handle this. We probably have three months to do this, since i
doubt the clock code is going to be part of the next merge.

      Andrew