On 01/23/2015 12:59 PM, Gregory CLEMENT wrote:
> On 23/01/2015 16:41, Maxime Ripard wrote:
>> The NDDB register holds the data that are needed by the read and write
>> commands.
>>
>> However, during a read PIO access, the datasheet specifies that after each 32
>> bits read in that register, when BCH is enabled, we have to make sure that
>> the
>> RDDREQ bit is set in the NDSR register.
>>
>> This fixes an issue that was seen on the Armada 385, and presumably other
>> mvebu
>> SoCs, when a read on a newly erased page would end up in the driver
>> reporting a
>> timeout from the NAND.
>>
>> Cc: <sta...@vger.kernel.org>
>
> It would help the stable maintainer if you could indicate since which commit
> or
> kernel release this fix should be applied.
>
This is a fix for the BCH support, namely commit 43bcfd2bb24a
"mtd: nand: pxa3xx: Add driver-specific ECC BCH support". The commit was merged
in v3.14.
However, this patch won't apply directly there. It will apply on commit
fa543bef72d6 "mtd: nand: pxa3xx: Add a read/write buffers markers"; which
was also merged in v3.14.
Therefore, I guess it's OK to say
Cc: <sta...@vger.kernel.org> # v3.14.x
>> Signed-off-by: Maxime Ripard <maxime.rip...@free-electrons.com>
>> ---
>> drivers/mtd/nand/pxa3xx_nand.c | 36 ++++++++++++++++++++++++++++++------
>> 1 file changed, 30 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/mtd/nand/pxa3xx_nand.c b/drivers/mtd/nand/pxa3xx_nand.c
>> index 96b0b1d27df1..320c2ab14d4e 100644
>> --- a/drivers/mtd/nand/pxa3xx_nand.c
>> +++ b/drivers/mtd/nand/pxa3xx_nand.c
>> @@ -480,6 +480,30 @@ static void disable_int(struct pxa3xx_nand_info *info,
>> uint32_t int_mask)
>> nand_writel(info, NDCR, ndcr | int_mask);
>> }
>>
>> +static void drain_fifo(struct pxa3xx_nand_info *info,
>> + void *data,
>> + int len)
^^
You don't need to split that line, it seems to fit 80 characters as is.
>> +{
>> + u32 *dst = (u32 *)data;
>> +
>> + if (info->ecc_bch) {
>> + while (len--) {
>> + *dst++ = nand_readl(info, NDDB);
>> +
>> + /*
>> + * According to the datasheet, when reading
>> + * from NDDB with BCH enabled, after each 32
>> + * bits reads, we have to make sure that the
>> + * NDSR.RDDREQ bit is set
>> + */
>> + while (!(nand_readl(info, NDSR) & NDSR_RDDREQ))
>> + cpu_relax();
>
> Are we sure that we won't be blocked here?
> If not, what about adding a timeout?
>
Definitely. I think we shouldn't have an infinite loop, no matter what the hw
specs say.
--
Ezequiel García, Free Electrons
Embedded Linux, Kernel and Android Engineering
http://free-electrons.com
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