linux-kernel - Re: [PATCH v4 2/2] OMAP:IOMMU:flush L1 and L2 caches

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Date:	Mon, 10 Sep 2012 15:55:17 +0530
From:	"Gupta, Ramesh" <grgupta@...com>
To:	Russell King - ARM Linux <linux@....linux.org.uk>
Cc:	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	linux-omap@...r.kernel.org, tony@...mide.com
Subject: Re: [PATCH v4 2/2] OMAP:IOMMU:flush L1 and L2 caches

Hi Russell,


On Sat, Sep 8, 2012 at 3:47 PM, Russell King - ARM Linux
<linux@....linux.org.uk> wrote:
> On Thu, Jul 05, 2012 at 10:50:24AM +0530, Gupta, Ramesh wrote:
>>  static void flush_iopgd_range(u32 *first, u32 *last)
>>  {
>> -     /* FIXME: L2 cache should be taken care of if it exists */
>> -     do {
>> -             asm("mcr        p15, 0, %0, c7, c10, 1 @ flush_pgd"
>> -                 : : "r" (first));
>> -             first += L1_CACHE_BYTES / sizeof(*first);
>> -     } while (first <= last);
>> +     flush_iommu_mem(first, last);
>> +     outer_flush_range(virt_to_phys(first), virt_to_phys(last));
>
> I think this would be safer if these operated on an area rather than a
> range - which means taking a start plus size.
>
>         phys_addr_t phys = virt_to_phys(start);
>
>         iommu_flush_area(start, size);
>         outer_flush_range(phys, phys + size);
>
> is safer than the above if virt_to_phys() is non-linear.

Agree, I will use the area.

>
>>               *iopgd = virt_to_phys(iopte) | IOPGD_TABLE;
>> -             flush_iopgd_range(iopgd, iopgd);
>> +             flush_iopgd_range(iopgd, iopgd + 1);
>
> And operating on a start + size also makes this kind of stuff clearer.

Sure, I will cleanup this and send an updated patch series.


Thank you for the inputs.

Best regards
Ramesh Gupta G
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