From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from metis.ext.pengutronix.de ([2001:67c:670:201:290:27ff:fe1d:cc33]) by bombadil.infradead.org with esmtps (Exim 4.85_2 #1 (Red Hat Linux)) id 1bKJyt-0002sz-OC for barebox@lists.infradead.org; Tue, 05 Jul 2016 06:37:16 +0000 Date: Tue, 5 Jul 2016 08:36:53 +0200 From: Sascha Hauer Message-ID: <20160705063653.GM20657@pengutronix.de> References: <1467471002-9613-1-git-send-email-akurz@blala.de> <20160704093704.GJ20657@pengutronix.de> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "barebox" Errors-To: barebox-bounces+u.kleine-koenig=pengutronix.de@lists.infradead.org Subject: Re: [PATCH] wdog: imx-wd: distinguish for WICR/WMCR support To: Alexander Kurz Cc: barebox@lists.infradead.org On Tue, Jul 05, 2016 at 12:40:29AM +0200, Alexander Kurz wrote: > > > On Mon, 4 Jul 2016, Sascha Hauer wrote: > > > On Sat, Jul 02, 2016 at 04:50:02PM +0200, Alexander Kurz wrote: > > > The IMX watchdog driver currently distinguishes two variants: imx1-wdt > > > using a 32-bit register interface and imx21-wdt with a 16-bit register > > > interface. > > > Further distinguishment is required: the i.MX21, i.MX27 and i.MX31 SOC > > > do provide a three register interface (WCR, WSR, WRSR) while later SOC > > > starting with i.MX25 provide two additional registers (WICR and WMCR). > > > The five-register interface is also used on i.MX35, and Cortex-A based > > > i.MX SOC. > > > > > > With commit 4cc0a3d9c547 ("wdog: imx-wd: Disable watchdog powerdown counter") > > > one of the extended registers (WMCR) got used first. > > > > > > Make imx-wd distinguish between the three and five register Watchdog Timers > > > and introduce the five register support as imx25-wdt. > > > > > > Note on DTS: keep the i.MX related DTS in sync with linux and make the > > > existing programming model fsl,imx21-wdt behave like fsl,imx25-wdt for > > > the mean time until this is addressed upstream in linux. > > > > > > fixes: 4cc0a3d9c547 ("wdog: imx-wd: Disable watchdog powerdown counter") > > > > So beginning with 4cc0a3d9c547 i.MX21, i.MX27 and i.MX31 accidently use > > the five-register interface. What are the practical consequences? Does > > the driver still work properly on these SoCs? > The access of this non-existing register triggers a crash of a barebox run > out of the factory shipped u-boot on an MX31 based Kindle-DX (u-boot gets > re-started, probably some abort handler) - I dont have any JTAG interface > running yet to see what's going on in detail. Just tested on i.MX27, it doesn't crash there. I noticed some time ago that i.MX27 and i.MX31 behave differently when accessing non existent registers. > > > > > I'm aksing because even with this patch... > > > > > .compatible = "fsl,imx21-wdt", > > > - .data = &imx21_wd_ops, > > > + /* FIXME: backward compaibility for imported linux DTS > > > + Most references to fsl,imx21-wdt from linux imported DTS > > > + linux actually mean fsl,imx25-wdt. Make fsl,imx21-wdt > > > + behave like fsl,imx25-wdt for the mean time until > > > + this is fixed there */ > > > + .data = &imx25_wd_ops, > > > + }, { > > > > ...device tree based i.MX21/27/31 boards still use the five-register > > interface. There are no i.MX21/31 based device tree boards, but there > > are some i.MX27 boards with device tree support. > Yes, this point is open. > I did not want to break the sync between the linux und barebox IMX DTS > stock. My Idea was: > 1) do this first fix in barebox which will not cover DTS (do > workaround "wdt21 behaves like wdt25") > 2) fix it in linux, wait till next rc which contains the fix > 3) linux DTS gets imported into barebox, and the workarkound wdt21 behaves > like wdt25" can be removed Sounds good. How about encapsulating the WMCR access in a if (cpu_is_mx25() || cpu_is_mx35() || cpu_is_mx51() || cpu_is_mx53() || cpu_is_mx6()) until we can properly distinguish between the different watchdog units? Sascha -- Pengutronix e.K. | | Industrial Linux Solutions | http://www.pengutronix.de/ | Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | _______________________________________________ barebox mailing list barebox@lists.infradead.org http://lists.infradead.org/mailman/listinfo/barebox