From mboxrd@z Thu Jan 1 00:00:00 1970 From: eric.y.miao@gmail.com (Eric Miao) Date: Sun, 5 Sep 2010 18:43:31 +0800 Subject: [PATCH] ARM: pxa: Fix pxa3xx-u2d crash when ULPI not used In-Reply-To: <4C835655.1080103@compulab.co.il> References: <1283546146-20000-1-git-send-email-marek.vasut@gmail.com> <201009051001.22816.marek.vasut@gmail.com> <4C8351F0.2040801@compulab.co.il> <201009051025.49256.marek.vasut@gmail.com> <4C835655.1080103@compulab.co.il> Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Sun, Sep 5, 2010 at 4:35 PM, Igor Grinberg wrote: > ?On 09/05/10 11:25, Marek Vasut wrote: >> Dne Ne 5. z??? 2010 10:16:48 Igor Grinberg napsal(a): >>> ?On 09/05/10 11:01, Marek Vasut wrote: >>>> Dne Ne 5. z??? 2010 09:54:31 Igor Grinberg napsal(a): >>>>> ?On 09/03/10 23:35, Marek Vasut wrote: >>>>>> In case the pxa3xx-u2d driver isn't used, probing of ohci-pxa27x will >>>>>> cause an ugly kernel crash (NULL pointer dereference in >>>>>> pxa3xx_u2d_start_hc(), because struct u2d is NULL and clk_enable() call >>>>>> will crash the kernel, trying to access it). >>>>> ohci code checks for pxa3xx cpu and only then runs start/stop hc. >>>> Exactly ... and in case "struct pxa3xx_u2d_ulpi *u2d" is NULL, clk_enable >>>> will crash the kernel. >>>> >>>>> pxa3xx_ulpi.c is compiled if CONFIG_PXA3xx is selected. >>>>> The device <-> driver binding should not be a problem, so the >>>>> pxa3xx_u2d_probe() will run. >>>>> The only case, I see, when struct u2d does not exist is failure of the >>>>> probe function. If this is the case, we are having an abnormal execution >>>>> and if your patch is dealing with this issue, shouldn't you comment it >>>>> as such? >>>> Not at all ... if the pxa3xx-u2d driver isn't loaded at all, the function >>>> (start/stop hc) is still called, but struct pxa3xx_u2d_ulpi *u2d is NULL. >>>> In this case, if you call clk_enable(u2d->clk), you crash the kernel >>>> (because u2d is NULL). >>> How, can it happen, that "pxa3xx-u2d driver isn't loaded at all"? >>> This can happen only if you rip out the device registration or hack a >>> Makefile. I don't see any other way... is there? >> If you don't call pxa3xx_set_u2d_info() ? > > Oh... right. > I've added it this way, so boards can control u2d existence and forgot it is there... > Buggy me... :( > Igor, So do you this as a proper fix, or there is better way out?