From: ext David Cohen <dacohen@xxxxxxxxx> Subject: Re: [PATCH] omap: iommu: disallow mapping NULL address Date: Mon, 7 Mar 2011 21:41:21 +0200 > On Mon, Mar 7, 2011 at 9:25 PM, Guzman Lugo, Fernando > <fernando.lugo@xxxxxx> wrote: >> On Mon, Mar 7, 2011 at 1:19 PM, David Cohen <dacohen@xxxxxxxxx> wrote: >>> On Mon, Mar 7, 2011 at 9:17 PM, Guzman Lugo, Fernando >>> <fernando.lugo@xxxxxx> wrote: >>>> On Mon, Mar 7, 2011 at 7:10 AM, Michael Jones >>>> <michael.jones@xxxxxxxxxxxxxxxx> wrote: >>>>> From e7dbe4c4b64eb114f9b0804d6af3a3ca0e78acc8 Mon Sep 17 00:00:00 2001 >>>>> From: Michael Jones <michael.jones@xxxxxxxxxxxxxxxx> >>>>> Date: Mon, 7 Mar 2011 13:36:15 +0100 >>>>> Subject: [PATCH] omap: iommu: disallow mapping NULL address >>>>> >>>>> commit c7f4ab26e3bcdaeb3e19ec658e3ad9092f1a6ceb allowed mapping >>>>> the NULL address if da_start==0. Force da_start to exclude the >>>>> first page. >>>> >>>> what about devices that uses page 0? ipu after reset always starts >>>> from 0x00000000 how could we map that address?? >>> >>> from 0x0? The driver sees da == 0 as error. May I ask you why do you want it? >> >> unlike DSP that you can load a register with the addres the DSP will >> boot, IPU core always starts from address 0x00000000, so if you take >> IPU out of reset it will try to access address 0x0 if not map it, >> there will be a mmu fault. > > Hm. Looks like the iommu should not restrict any da. The valid da > range should rely only on pdata. > Michael, what about just update ISP's da_start on omap-iommu.c file? > Set it to 0x1000. > > Hiroshi, any opinion? We have assumed that 'da == 0' is NULL so far. According to Fernando's explanation, 'da == 0' should be allowed in iovmm layer by default. -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
