On Saturday, February 01, 2014 at 12:05:29 PM, Lukasz Majewski wrote: > On Sat, 1 Feb 2014 03:55:20 +0100 > > Marek Vasut <ma...@denx.de> wrote: > > On Friday, January 31, 2014 at 01:16:27 PM, Lukasz Majewski wrote: > > > The Samsung's UDC driver is not anymore copying data from USB > > > requests to data aligned internal buffers. Now it works directly in > > > data allocated in the upper layers like UMS, DFU, THOR. > > > > > > This change is possible since those gadgets now take care to > > > allocate buffers aligned to cache line (CONFIG_SYS_CACHELINE_SIZE ). > > > > > > Previously the UDC needed to copy this data to internal aligned > > > buffer to prevent from unaligned access exceptions. > > > > > > Test condition > > > - test HW + measurement: Trats - Exynos4210 rev.1 > > > - test HW Trats2 - Exynos4412 rev.1 > > > 400 MiB compressed rootfs image download with `thor 0 mmc 0` > > > > > > Measurement: > > > Transmission speed: 27.04 MiB/s > > > > > > Change-Id: I1df1fbafc72ec703f0367ddee3fedf3a3f5523ed > > > Signed-off-by: Lukasz Majewski <l.majew...@samsung.com> > > > Cc: Marek Vasut <ma...@denx.de> > > > > You should use ROUND_UP(), not ROUND() throughout the patch. > > Otherwise you might fail to flush/invalidate the last little bit of > > data in some cacheline. > > I might overlooked something, so please correct me if needed. > > I allocate buffers in gadgets which are aligned to cache line with > starting address and its size is a multiplication of cache line size > (so I will not trash data allocated next to it when I invalidate cache). > > In the code I'm using ROUND to invalidate/flush more data than needed > (ROUND(176, 32) = 192). I'm prepared for this since buffer in gadget is > properly allocated (with DEFINE_CACHE_ALIGN_BUFFER() which uses > roundup() internally).
The problem is in case you receive buffer which is aligned to cacheline with it's start, but is [(k * cacheline_size) + (cacheline_size / 2) - 1] big. I think it's unlikely, but if this happens, you will get corruption, right ? You might actually want to check for this condition and throw a warning in such a case. I understand your argument with trying to not trash data, but then you will get a corruption during transfer, right ? Best regards, Marek Vasut _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
