From mboxrd@z Thu Jan 1 00:00:00 1970 From: Shawn Guo Subject: Re: [PATCH V2] spmi: pmic-arb: Enforce the ownership check optionally Date: Fri, 1 Sep 2017 11:00:51 +0800 Message-ID: <20170901030049.GD3787@dragon> References: <20170822085541.GB3685@dragon> <20170822203132.GC21656@codeaurora.org> <20170824121818.GE3685@dragon> <20170824183701.GN21656@codeaurora.org> <20170825074324.GF3685@dragon> <20170825231818.GP21656@codeaurora.org> <20170826034636.GG3685@dragon> <20170830210203.GS21656@codeaurora.org> <20170831083727.GA3787@dragon> <20170901013048.GK21656@codeaurora.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20170901013048.GK21656-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org> Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Stephen Boyd Cc: Kiran Gunda , gregkh-hQyY1W1yCW8ekmWlsbkhG0B+6BGkLq7r@public.gmane.org, Rob Herring , Mark Rutland , Abhijeet Dharmapurikar , David Collins , devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-arm-msm-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-arm-msm-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-arm-msm@vger.kernel.org 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-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751419AbdIADBF (ORCPT ); Thu, 31 Aug 2017 23:01:05 -0400 Received: from mail.kernel.org ([198.145.29.99]:50040 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751258AbdIADBD (ORCPT ); Thu, 31 Aug 2017 23:01:03 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org BE7D721AF9 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=shawnguo@kernel.org Date: Fri, 1 Sep 2017 11:00:51 +0800 From: Shawn Guo To: Stephen Boyd Cc: Kiran Gunda , gregkh@linuxfoundation.org, Rob Herring , Mark Rutland , Abhijeet Dharmapurikar , David Collins , devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-arm-msm-owner@vger.kernel.org Subject: Re: [PATCH V2] spmi: pmic-arb: Enforce the ownership check optionally Message-ID: <20170901030049.GD3787@dragon> References: <20170822085541.GB3685@dragon> <20170822203132.GC21656@codeaurora.org> <20170824121818.GE3685@dragon> <20170824183701.GN21656@codeaurora.org> <20170825074324.GF3685@dragon> <20170825231818.GP21656@codeaurora.org> <20170826034636.GG3685@dragon> <20170830210203.GS21656@codeaurora.org> <20170831083727.GA3787@dragon> <20170901013048.GK21656@codeaurora.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170901013048.GK21656@codeaurora.org> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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