2016-03-22 16:20 GMT+08:00 G Gregory <graeme.gregory@xxxxxxxxxx>: > On 22 March 2016 at 02:17, Jun Nie <jun.nie@xxxxxxxxxx> wrote: >> 2016-03-22 10:06 GMT+08:00 Timur Tabi <timur@xxxxxxxxxxxxxx>: >>> Jun Nie wrote: >>>> >>>> That's a fair comment. I suppose all platform need to enable clock for >>>> the device. For device tree case, we need these code for clock >>>> enabling. >>> >>> >>> But why do you need to enable the clock? The pl011 driver works fine for >>> every platform without your patch. If the ZTE platform needs to call >>> clk_get() in order to work, than that is something different about your >>> platform. >> >> ARM/ST pl011 is amba device and use pl011_probe() for initialization, >> which call these clock enabling code for every device. You introduced >> platform device driver entry for pl011 and only sbsa use platform >> device probe method currently. I am trying to reuse this probe >> function, so need to add clock enabling code in this function. >> >> If you did not find any issue in sbsa device tree case, I guess the >> clock is always enabled. For mobile platform, clock is auto gated for >> power saving in most of cases. >> >>> >>>> For ACPI case, it may be handled automatically. If you agree >>>> my opinion, I will move these lines to patch 1. Please correct me if I >>>> am wrong. >>> >>> >>> I think you need to create a separate patch that adds that call, and make >>> sure it's tested by other platforms before it gets accepted. >> >> These code only impact sbsa device as only sbsa device is initialized >> via platform driver entry. So only your flavor is need for testing the >> code. Thanks! :-) >> > In SBSA mode the UART clock is always enabled by the firmware and > there are no baud rate registers so we don't need to know the value of > the clock. In ACPI there is no method to represent the clock. So if > you add lines to unconditionally require a clock you will break SBSA > mode in ACPI. > > Graeme Right, Timur also already point out breakage of ACPI case. So I plan to move clocking enabling code to device tree case handling. Do you still have any other concern? Jun -- To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
