On Thu, Aug 31, 2017 at 06:30:48PM -0700, Stephen Boyd wrote: > On 08/31, Shawn Guo wrote: > > On Wed, Aug 30, 2017 at 02:02:03PM -0700, Stephen Boyd wrote: > > > On 08/26, Shawn Guo wrote: > > > > On Fri, Aug 25, 2017 at 04:18:18PM -0700, Stephen Boyd wrote: > > > > > > > > > > Right. Does the GPIO work? If so, it sounds like the read/write > > > > > access checks in spmi pmic arb don't work properly. > > > > > > > > The check works. With the check in there, PM8916 GPIO doesn't work. > > > > However, the consequence is that not only user3 but all GPIO leds under > > > > 'leds' node will fail to register, because any GPIO led's failing on > > > > create_gpio_led() makes leds-gpio driver probe fail as a while. That's > > > > how leds-gpio driver works. > > > > > > > > Also, per schematics, PM8916 GPIO1 is indeed routed to user3 LED on > > > > db410c board. Why do you think apq8016-sbc device tree shouldn't use > > > > the GPIO for that at all? Isn't it firmware's fault that the ownership > > > > of the peripheral is not properly configured? > > > > > > If the ownership was not properly configured in the firmware, > > > then I imagine it would mean that we can't control the GPIO for > > > the LED. But that doesn't seem to be true. I can see on my board > > > that I get impermissible write failures on the GPIO when > > > controlling the GPIO brightness, but it doesn't actually matter > > > because the led still lights up. So the checks for write/read > > > permission seem incorrect, or they're not being enforced. > > > > I'm not sure what is happening on your side. As I said above, with the > > 4.13-rc series, leds-gpio driver doesn't probe at all, due to the > > impermissible write to PM8916 GPIO in function create_gpio_led(), and > > none of the LEDs lights up on my board. > > > > Yep. I understand all that. > > Sorry, I forgot to mention I modified the SPMI PMIC arb code on > v4.13-rc7 to continue even though a permission fault may happen > by deleting the 'return -EPERM' lines. So the LED GPIO driver is > still probing for me, and I see that the GPIOs work regardless of > any permission problems that may have been enforced in the > hardware. I thought the permission checks that the software is > looking at to return EPERM were enforced in hardware, but that > doesn't seem to be the case. That's all I was wondering about. Ah, okay. You were asking about the check in hardware, while I was talking about the check in software. Yes, now we are on the same page: the permission check in hardware seems not enforced. That's why LED works after we merely remove the check in SPMI PMIC arb driver code. Shawn -- 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
