On Fri, Mar 20, 2015 at 3:54 PM, Daniel Mack <zon...@gmail.com> wrote: > Hi, > > On 03/20/2015 12:24 PM, Yegor Yefremov wrote: >> I've also put printf() into omap_nand_read_prefetch8() just to make >> sure it is called - it was called. > > Does it fall back to polled mode because the engine is busy maybe? See > the comment in the code that deals with the return value of > __read_prefetch_aligned(). Not that I'd be aware of such an issue, but > maybe you need to enable to enable some module or clock?
I've seen this fallback comment and added printf to ret < 0 case and in __read_prefetch_aligned(). I had no cases, where fallback was invoked. I've also a suspicion, that some clocks settings are missing. Will have to compare register values with Linux ones. >> Further ideas? > > It's been a while, but when I worked on cutting down the boot times of a > custom AM335x board months ago, these were the steps that I took: > > > * I tweaked the NAND timing values in the DTS, and then looked at the > GPMC timing values Linux calculated from that and copied it over to > U-Boot. This gave a NAND read speed-up of ~20-30% in comparison to the > defaults U-Boot ships with. > > * Implementing the GPMC prefetch operations boosted the speed by of raw > NAND reads by approximately factor 2. > > * The NAND bad block table scan was reduced to the first 64 blocks, > because this is all I cared for from U-Boot anyway, and Linux will do > the same anyway at a later point. This brought down the scan process > from ~2s to some milliseconds. > > * In the SPL code, the CPU was put in GHz mode as early as possible. > That improved load times again, and also reduced the time spent in the > kernel decompressor. Do you mean am33xx_spl_board_init()? In theory it reads ID and sets desired MPU/Core voltage. But I'll look at this once again. >> I Linux I had ti,nand-xfer-type = "polled";. After replacing it with >> ti,nand-xfer-type = "prefetch-polled"; I now get >> >> # dd if=/dev/mtdblock5 of=/dev/null bs=2M count=8 >> 8+0 records in >> 8+0 records out >> 16777216 bytes (17 MB) copied, 2.58744 s, 6.5 MB/s >> >> instead of: >> >> # dd if=/dev/mtdblock5 of=/dev/null bs=2M count=8 >> 8+0 records in >> 8+0 records out >> 16777216 bytes (17 MB) copied, 6.05157 s, 2.8 MB/s >> >> Do I see it right, that DMA support is not implemented in am33xx.dtsi? > > Right, I just double-checked with the DTS we were using. It had no > specific "ti,nand-xfer-type" setting, so it should default to > "prefetch-polled". So it seems DMA is not in place for this board and > the gpmc-nand driver. Sorry for the confusion. > > > Daniel _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
