On Mon, Sep 15, 2014 at 10:12:10PM +0200, Boris BREZILLON wrote: > On Mon, 15 Sep 2014 22:43:02 +0800 > Huang Shijie <shij...@gmail.com> wrote: > > > On Sat, Sep 13, 2014 at 10:38:41AM -0700, Brian Norris wrote: > > > On Sat, Sep 13, 2014 at 11:36:24PM +0800, Huang Shijie wrote: > > > > On Fri, Sep 12, 2014 at 02:30:50PM +0200, Boris BREZILLON wrote: > > > > > This test validates what's returned by ecc_strength file in sysfs > > > > > (which in turn is specified by the NAND controller when initializing > > > > > the NAND chip). > > > > > > > > > > Doing this should not imply knowing the ECC algorithm in use in the > > > > > NAND controller or the layout used to store data on NAND. > > > > the difficulty is that the ECC parity area can be not byte aligned. > > > > > > Is there a problem with just rounding up to the nearest byte alignment > > > and ignoring the few bits that are wasted? > > > > I feel a little confused with the two hooks. > > > > does the ecc->write_page_raw need to write the ECC parity data? > > Depending on the oob_required argument, it might be allowed to > overwrite the ECC bytes even if this implies breaking page reliability > (which is exactly what's expected). > > When using raw write with with oob write option the writer should take > care of regenerating ECC bytes (which you said was impossible in GPMI > case) or copying them from a previous raw read. Thanks for the explanation.
If we do not write the OOB, should we write the ECC bytes? The hooks should comment clearly about how to implement them :( > > Here is a real example of what one could test with raw write + oob: > 1) read a page in raw mode > 2) flip some bits in the generated ECC bytes (or what you references as > parity data) (this case can actually happen in real life) > 3) write the modified page in raw mode > 4) read back the same page in normal and check that ECC correction still > works as expected the nandbiterr test mode does the test as above. But i think the multi-writes to the same page should occur only for the SLC nand. I will read your new patch set carefully in this weekend. thanks Huang Shijie -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
