On Sun, May 30, 2010 at 06:42:59PM +0200, David Lanzendörfer wrote: > GNUtoo asked me to send the following mail also to this ML. > Just for information. > Here it is. > ----------------Sent to: Arve Hjønnevåg <arve@xxxxxxxxxxx>---------------- > Hello > I'm working on the FSO projects msm port. > So we came across the problem, that we can not install UBIFS rootimages > on the internal NAND of htcdream, nexus-one and other htc devices, > because of the missing subpagesize reading functionality issue. > The only filesystem which accepts only block-size reading is YAFFS2, > but YAFFS2 doesnt implement compression. > So we loose a lot of space on the internal memory, what leads us to the issue, > that SHR-full doesnt fit into internal memory. > I git blamed the driver and found your name in the most of the lines, > so I guess, that this driver is pretty known to you, and you would perhaps have > some tips for us, or even give us a rudimentary patch, which allows expansion. The NAND controller on the MSM has limited support for subpage operations. The problem is that it does ECC across the entire page data. This is necessary in order to support MLC NAND devices. Is the requirement to do subpage read, or subpage writing? Subpage writing is not possible on MLC NAND (it isn't even permitted to overwrite data to zero things out). Depending on which data is needed, subpage reading could be done, but would transfer at least 1/4 of the page anyway. David -- To unsubscribe from this list: send the line "unsubscribe linux-arm-msm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
