Hi!
I comment to latest patch.
Best regards,
Nobuhiro
2014-11-13 1:23 GMT+09:00 Simon Glass <s...@chromium.org>:
> On 22 August 2014 03:15, Thierry Reding <thierry.red...@gmail.com> wrote:
>> On Wed, Aug 20, 2014 at 01:29:57PM -0600, Stephen Warren wrote:
>>> On 08/18/2014 02:00 AM, Thierry Reding wrote:
>>> >From: Thierry Reding <tred...@nvidia.com>
>>> >
>>> >RX and TX descriptor rings should be aligned to 256 byte boundaries. Use
>>> >the DEFINE_ALIGN_BUFFER() macro to define the buffers so that they don't
>>> >have to be manually aligned later on. Also make sure that the buffers do
>>> >align to cache-line boundaries in case the cache-line is higher than the
>>> >256 byte alignment requirements of the NIC.
>>> >
>>> >Also add a warning if the cache-line size is larger than the descriptor
>>> >size, because the driver may discard changes to descriptors made by the
>>> >hardware when requeuing RX buffers.
>>>
>>> >@@ -909,6 +899,18 @@ static int rtl_init(struct eth_device *dev, bd_t *bis)
>>>
>>> >+ /*
>>> >+ * Warn if the cache-line size is larger than the descriptor size. In
>>> >+ * such cases the driver will likely fail because the CPU needs to
>>> >+ * flush the cache when requeuing RX buffers, therefore descriptors
>>> >+ * written by the hardware may be discarded.
>>> >+ */
>>> >+ if (ARCH_DMA_MINALIGN > sizeof(struct RxDesc))
>>> >+ printf("WARNING: cache-line size is larger than descriptor
>>> >size\n");
>>>
>>> I'd be tempted to make that a compile-time #error (or perhaps just a
>>> #warning) Perhaps #error would break compilation of existing boards though?
>>
>> There are two SH4 boards that use the rtl8169 (r7780mp and sh7785lcr)
>> for which this condition is true, so #error would break them (well,
>> technically not r7780mp since it comments out CONFIG_RTL8169 in the
>> configuration). I'll make it a #warning instead.
>
> Adding the maintainer for comment.
>
> Regards,
> Simon
--
Nobuhiro Iwamatsu
iwamatsu at {nigauri.org / debian.org}
GPG ID: 40AD1FA6
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