Hi Guenter, On 21 May 2015 at 23:28, Guenter Roeck <linux@xxxxxxxxxxxx> wrote: > On Thu, May 21, 2015 at 08:09:02AM -0500, Timur Tabi wrote: >> Guenter Roeck wrote: >> >> >> >>+static unsigned int sbsa_gwdt_get_timeleft(struct watchdog_device *wdd) >> >>+{ >> >>+ struct sbsa_gwdt *gwdt = to_sbsa_gwdt(wdd); >> >>+ u64 timeleft = sbsa_gwdt_get_wcv(wdd) - arch_counter_get_cntvct(); >> >>+ >> > >> >Still not happy about the use of arch_counter_get_cntvct >> >instead of using the clock subsystem. I am quite sure this could be done, >> >possibly through arch_sys_counter, though at this point I am getting wary >> >of bringing it up, so I guess I'll just let it go. >> >> You made the same comment with my driver, and I keep asking for >> clarification. The clk_get_sys() API does not work on my system, because >> there are not clocks defined. That must be an ACPI limitation that I can't >> fix. >> > Would it be possible to define such clocks ? > >> The alternative to arch_counter_get_cntvct() is arch_timer_read_counter(), >> which is not exported. So we have two choices, >> >> 1) Continue to use arch_counter_get_cntvct(), which works on all ARM64 >> platforms that this driver supports anyway >> >> 2) Export arch_timer_read_counter() >> >> I prefer option #1. >> > Do we have any feedback from the arm maintainers ? > > My problem is that I don't want to be the first one to permit using > those functions outside architecture and clock code. If we do this, > we should get an Ack from an arm maintainer specifically for the use > of arch_counter_get_cntvct() and arch_timer_get_rate(). IMO, we may need to use arch_timer_read_counter. Reason: Once the Linux kernel has KVM support and is in hyp mode. we may need to use arch_counter_get_cntpct. So arch_timer driver have helped us to make arch_timer_read_counter point to the right function. and arch_timer_read_counter is in the include/clocksource/arm_arch_timer.h, just like arch_timer_get_rate as a interface > > Thanks, > Guenter > -- > To unsubscribe from this list: send the line "unsubscribe devicetree" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- Best regards, Fu Wei Software Engineer Red Hat Software (Beijing) Co.,Ltd.Shanghai Branch Ph: +86 21 61221326(direct) Ph: +86 186 2020 4684 (mobile) Room 1512, Regus One Corporate Avenue,Level 15, One Corporate Avenue,222 Hubin Road,Huangpu District, Shanghai,China 200021 -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html