[PATCH v2 1/4] ARM i.MX6: use reserved bit for mxs phy clock gate

[Shawn Guo]

On Tue, Jan 15, 2013 at 02:08:34PM +0800, Peter Chen wrote:
> For mxs-phy user i.mx6q, the PHY's clock is controlled by
> hardware automatically, the software only needs to enable it
> at probe, disable it at remove. During the runtime,
> we don't need to control it. So for the usbphy clk policy:
> 
> - Keep refcount for usbphy as clk framework needs to know if
> it is off or on.

Just checked the reference manual, it seems that not only bit 6
(EN_USB_CLKS) but also bit 12 (POWER) are controlled by USB hardware.
If this is true, I think that PLL3 and PLL7 are really designed for
USB PHY use only.  Do you actually see other real users of these two
PLLs on imx6q besides USB PHY?  If not, we can just provide a dummy
clock to mxs-phy driver on imx6q, and keep real clocks usbphy1 and
usbphy2 there for platform init function to enable them if USB support
is built in.  Then, we can save all these dirty hacks.  Thoughts?

Shawn

> - Use reserved bit, in that case, clk_enable/disable will
> only update refcount, but without any hardware effects.
> 
> Signed-off-by: Peter Chen <peter.chen at freescale.com>
> ---
> Changes for v2:
> - Use reserved bit for usb phy clk control
> 
>  arch/arm/mach-imx/clk-imx6q.c |   10 ++++++++--
>  1 files changed, 8 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/arm/mach-imx/clk-imx6q.c b/arch/arm/mach-imx/clk-imx6q.c
> index 7f2c10c..85dcc89 100644
> --- a/arch/arm/mach-imx/clk-imx6q.c
> +++ b/arch/arm/mach-imx/clk-imx6q.c
> @@ -208,8 +208,14 @@ int __init mx6q_clocks_init(void)
>  	clk[pll7_usb_host] = imx_clk_pllv3(IMX_PLLV3_USB,	"pll7_usb_host","osc", base + 0x20, 0x3);
>  	clk[pll8_mlb]      = imx_clk_pllv3(IMX_PLLV3_MLB,	"pll8_mlb",	"osc", base + 0xd0, 0x0);
>  
> -	clk[usbphy1] = imx_clk_gate("usbphy1", "pll3_usb_otg", base + 0x10, 6);
> -	clk[usbphy2] = imx_clk_gate("usbphy2", "pll7_usb_host", base + 0x20, 6);
> +	/*
> +	 * Bit 20 is the reserved and read-only bit, we do this only for:
> +	 * - Do nothing for usbphy clk_enable/disable
> +	 * - Keep refcount when do usbphy clk_enable/disable, in that case,
> +	 * the clk framework can know the USB phy clk is on or off
> +	 */
> +	clk[usbphy1] = imx_clk_gate("usbphy1", "pll3_usb_otg", base + 0x10, 20);
> +	clk[usbphy2] = imx_clk_gate("usbphy2", "pll7_usb_host", base + 0x20, 20);
>  
>  	clk[sata_ref] = imx_clk_fixed_factor("sata_ref", "pll6_enet", 1, 5);
>  	clk[pcie_ref] = imx_clk_fixed_factor("pcie_ref", "pll6_enet", 1, 4);
> -- 
> 1.7.0.4
> 
>