From: Vipin Kumar <vipin.kumar@st.com>
To: u-boot@lists.denx.de
Subject: [U-Boot] [PATCH 1/2] drivers/net/designware, do an explicit memory access instead of implicit, re-written assignments to use readl() and writel(), all of this as preperation for making the driver able to work in a cached environment (I$D$ support).
Date: Wed, 23 Jan 2013 15:46:31 +0530 [thread overview]
Message-ID: <50FFB87F.3060609@st.com> (raw)
In-Reply-To: <20130123075559.49f94e5f@lilith>
On 1/23/2013 12:25 PM, Albert ARIBAUD wrote:
> Hi Vipin,
>
>> My first feeling is that the descriptors are allocated as Normal
>> Cachabale memory and it would not help to access them using readl/writel
>>
>> Should the desciptors be allocated as non-cachable memory. If yes then
>> how to do that in u-boot
>>
>> I suppose the rest of the code would be better reviewed if we know about
>> this
>>
>> Vipin
>
> I would say that yes, descriptors are allocated in DRAM, so they are
> cacheable.
>
> And no, we don't need to allocate them non-cacheable, although in this
> case we need to use cache flush and invalidate calls. I would suggest
> doing so rather than allocating the descriptors non cacheable, because
> using non-cacheable memory makes the dependency between the driver and
> cache codes implicit (and thus more prone to improperly thought out
> changes in either code) and the memory usage more complex, while
> explicit cache operations make the relationship explicit.
>
Yes, got it. Thanks Albert
Frank, so in that case rather changing the code to use readl/writel,
cache flush and invalidate operations need to be performed at
appropriate places
Regards
Vipin
> One can always not cache descriptors if you one wants to, without this
> decision breaking driver functionality.
>
> Amicalement,
next prev parent reply other threads:[~2013-01-23 10:16 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-01-22 14:10 [U-Boot] [PATCH 0/2] make u-boot/drivers/net/designware cache supportive Frank Dols
2013-01-22 14:10 ` [U-Boot] [PATCH 1/2] drivers/net/designware, do an explicit memory access instead of implicit, re-written assignments to use readl() and writel(), all of this as preperation for making the driver able to work in a cached environment (I$D$ support) Frank Dols
2013-01-23 5:29 ` Vipin Kumar
2013-01-23 6:55 ` Albert ARIBAUD
2013-01-23 10:16 ` Vipin Kumar [this message]
2013-01-23 10:21 ` Albert ARIBAUD
2013-01-24 9:58 ` Frank Dols
[not found] ` <1869199372336F41A75F0B381AC8B48A028B6B@DE02WEMBX1.internal.synopsys.com>
[not found] ` <511879F4.206@st.com>
2013-03-01 10:05 ` [U-Boot] FW: " Frank Dols
2013-11-22 19:03 ` Joe Hershberger
2013-01-22 14:10 ` [U-Boot] [PATCH 2/2] u-boot/drivers/net/designware with cache support Frank Dols
2013-01-23 4:11 ` [U-Boot] [PATCH 0/2] make u-boot/drivers/net/designware cache supportive Vipin Kumar
2013-06-13 11:28 ` Joe Hershberger
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