[PATCH] ARM: imx: fix shared gate clock

[Fabio Estevam]

On Sun, Jul 6, 2014 at 11:53 PM, Shawn Guo <shawn.guo at freescale.com> wrote:
> Let's say clock A and B are two gate clocks that share the same register
> bit in hardware.  Therefore they are registered as shared gate clocks
> with imx_clk_gate2_shared().
>
> In a scenario that only clock A is enabled by clk_enable(A) while B is
> not used, the shared gate will be unexpectedly disabled in hardware.
> It happens because clk_enable(A) increments the share_count from 0 to 1,
> while clock B is unused to clock core, and therefore the core function
> will just disable B by calling clk->ops->disable() directly.  The
> consequence of that call is share_count is decremented to 0 and the gate
> is disabled in hardware, even though clock A is still in use.
>
> The patch fixes the issue by initializing the share_count per hardware
> state and returns enable state per share_count from .is_enabled() hook,
> in case it's a shared gate.
>
> While at it, add a check in clk_gate2_disable() to ensure it's never
> called with a zero share_count.
>
> Reported-by: Fabio Estevam <fabio.estevam at freescale.com>
> Fixes: f9f28cdf2167 ("ARM: imx: add shared gate clock support")
> Signed-off-by: Shawn Guo <shawn.guo at freescale.com>
> ---
> Fabio,
>
> Per my testing, it fixes the shared gate clock issue you reported.
> But I'd like to get your confirmation before I ask arm-soc folks to
> apply it for 3.16-rc.

I can get audio working now and I have also inspected CCGR5 register
and it looks correct now:

Tested-by: Fabio Estevam <fabio.estevam at freescale.com>