Messages in this thread | | | Date | Mon, 18 Aug 2014 19:48:53 +0800 | From | Shawn Guo <> | Subject | Re: [RFC] usb issue on imx27: 3 clocks are needed |
| |
On Mon, Aug 18, 2014 at 06:35:53PM +0800, Chen Peter-B29397 wrote: > > > On Mon, Aug 18, 2014 at 05:00:59PM +0800, Peter Chen wrote: > > > On Sat, Aug 16, 2014 at 05:38:30PM +0200, Philippe Reynes wrote: > > > > Hi all, > > > > > > > > i.MX27's usb needs three clocks (usb_ipg_gate, usb_ahb_gate and > > > > usb_div) but the current chipidea driver implementation, and > > > > devicetree, provides only ipg and ahb. Consequently, if the > > > > bootloader don't enable the last one, the kernel will crash. > > > > > > > > Our approach/idea is to add a second, optionnal, clock in > > > > ci_hdrc_imx.c with 'per' name in devicetree and to add clock name > > 'main_clk' for mandatory clock. > > > > This approach it correct? Or an other approach seems better? > > > > Thank you very much for your point of view. > > > > > > > > > > It is ok for me to have ipg, ahb and per clocks at driver, but how can > > > you maintain DT consistent? > > > > Adding new clock as optional one will just maintain the DT compatibility. > > > > How to handle node_usb_soc1's clock which is without clk name to consistent with three > clocks for node_usb_soc2 at driver? Except for adding some platform judge code at > driver, do you have other solutions? > > node_usb_soc1: { > clocks = <&clks IMX6_CLK_USBOH3>; > }; > > node_usb_soc2: { > clocks = <&clks IMX27_CLK_USBIPG>, <&clks IMX27_CLK_USBOH3>, <&clks IMX27_CLK_USBPER>; > clock-names = "ipg", "ahb", "per"; > };
Oh, what I was talking about is we need to ensure the new kernel (handling additional clocks) doesn't break old/existing DTB. That's what we call DT compatibility.
There is no DT consistency to maintain. If there is only one clock for USB on i.MX6 while 3 clocks on i.MX27, that's something USB driver needs to handle, as clearly these two SoCs have different programming model on USB device.
Shawn
| |