| Message ID | ce9ab5790912310420h20beb04csba060b3f5cfeee92@mail.gmail.com |
|---|---|
| State | New, archived |
| Headers | show |
On Thu, Dec 31, 2009 at 4:20 AM, Vimal Singh <vimal.newwork@gmail.com> wrote: > On Wed, Dec 30, 2009 at 3:17 AM, Steve Sakoman <sakoman@gmail.com> wrote: >> On Tue, Dec 29, 2009 at 12:38 PM, Steve Sakoman <sakoman@gmail.com> wrote: >> >>> I can confirm that this issue exists on Overo too. Sadly, switching >>> to 16 bit reads does not fix the issue for me. I'll start digging to >>> see if I can find what's broken. >> >> I can also confirm that there are days when I am not even capable of >> applying a patch properly :-( >> >> Switching to 16 bit read accesses does indeed fix the ECC issue on Overo too. >> >> Which still leaves us needing to find the root cause of the breakage . . . > > There is a bug in nand prefetch read routine, which comes into effect > only if nand device is a 16-bit device (as we have in zoom boards). > This bug is effective only with below combination of conditions: > 1. nand deivce, in use, is a 16 bit device > 2. nand driver supports 'subpage' read > 3. SW ECC is in use > > This was not seen old kernel (ex: .23), because when, in early days, > we tested this (nand prefetch read in LDP boards) there was no > 'subpage read' support. > Later when we had subpage read in (.27) kernel, we had hw ecc enabled > always in our internal tree. So, we missed this bug. > > Here is a patch to fix this issue: > > diff --git a/drivers/mtd/nand/omap2.c b/drivers/mtd/nand/omap2.c > index 1bb799f..75004fe 100644 > --- a/drivers/mtd/nand/omap2.c > +++ b/drivers/mtd/nand/omap2.c > @@ -295,11 +295,14 @@ static void omap_read_buf_pref(struct > u32 *p = (u32 *)buf; > > /* take care of subpage reads */ > - for (; len % 4 != 0; ) { > - *buf++ = __raw_readb(info->nand.IO_ADDR_R); > - len--; > + if (len % 4) { > + if (info->nand.options & NAND_BUSWIDTH_16) > + omap_read_buf16(mtd, buf, len % 4); > + else > + omap_read_buf8(mtd, buf, len % 4); > + p = (u32 *) (buf + len % 4); > + len -= len % 4; > } > - p = (u32 *) buf; > > /* configure and start prefetch transfer */ > ret = gpmc_prefetch_enable(info->gpmc_cs, 0x0, len, 0x0); I tested this on Overo and can confirm that it fixes the issue. Steve
On Thu, 2009-12-31 at 17:50 +0530, Vimal Singh wrote: > There is a bug in nand prefetch read routine, which comes into effect > only if nand device is a 16-bit device (as we have in zoom boards). > This bug is effective only with below combination of conditions: > 1. nand deivce, in use, is a 16 bit device > 2. nand driver supports 'subpage' read > 3. SW ECC is in use > > This was not seen old kernel (ex: .23), because when, in early days, > we tested this (nand prefetch read in LDP boards) there was no > 'subpage read' support. > Later when we had subpage read in (.27) kernel, we had hw ecc enabled > always in our internal tree. So, we missed this bug. > > Here is a patch to fix this issue: > > diff --git a/drivers/mtd/nand/omap2.c b/drivers/mtd/nand/omap2.c > index 1bb799f..75004fe 100644 > --- a/drivers/mtd/nand/omap2.c > +++ b/drivers/mtd/nand/omap2.c > @@ -295,11 +295,14 @@ static void omap_read_buf_pref(struct > u32 *p = (u32 *)buf; > > /* take care of subpage reads */ > - for (; len % 4 != 0; ) { > - *buf++ = __raw_readb(info->nand.IO_ADDR_R); > - len--; > + if (len % 4) { > + if (info->nand.options & NAND_BUSWIDTH_16) > + omap_read_buf16(mtd, buf, len % 4); > + else > + omap_read_buf8(mtd, buf, len % 4); > + p = (u32 *) (buf + len % 4); > + len -= len % 4; > } > - p = (u32 *) buf; > > /* configure and start prefetch transfer */ > ret = gpmc_prefetch_enable(info->gpmc_cs, 0x0, len, 0x0); Pushed this patch to my l2-mtd-2.6.git/dunno.
On Sun, Jan 10, 2010 at 2:16 PM, Artem Bityutskiy <dedekind1@gmail.com> wrote: > On Thu, 2009-12-31 at 17:50 +0530, Vimal Singh wrote: >> There is a bug in nand prefetch read routine, which comes into effect >> only if nand device is a 16-bit device (as we have in zoom boards). >> This bug is effective only with below combination of conditions: >> 1. nand deivce, in use, is a 16 bit device >> 2. nand driver supports 'subpage' read >> 3. SW ECC is in use >> >> This was not seen old kernel (ex: .23), because when, in early days, >> we tested this (nand prefetch read in LDP boards) there was no >> 'subpage read' support. >> Later when we had subpage read in (.27) kernel, we had hw ecc enabled >> always in our internal tree. So, we missed this bug. >> >> Here is a patch to fix this issue: >> >> diff --git a/drivers/mtd/nand/omap2.c b/drivers/mtd/nand/omap2.c >> index 1bb799f..75004fe 100644 >> --- a/drivers/mtd/nand/omap2.c >> +++ b/drivers/mtd/nand/omap2.c >> @@ -295,11 +295,14 @@ static void omap_read_buf_pref(struct >> u32 *p = (u32 *)buf; >> >> /* take care of subpage reads */ >> - for (; len % 4 != 0; ) { >> - *buf++ = __raw_readb(info->nand.IO_ADDR_R); >> - len--; >> + if (len % 4) { >> + if (info->nand.options & NAND_BUSWIDTH_16) >> + omap_read_buf16(mtd, buf, len % 4); >> + else >> + omap_read_buf8(mtd, buf, len % 4); >> + p = (u32 *) (buf + len % 4); >> + len -= len % 4; >> } >> - p = (u32 *) buf; >> >> /* configure and start prefetch transfer */ >> ret = gpmc_prefetch_enable(info->gpmc_cs, 0x0, len, 0x0); > > Pushed this patch to my l2-mtd-2.6.git/dunno. > I have posted this patch formally in patch series: [PATCH 0/3][NAND][OMAP]: fixing omap nand driver issues Corresponding patch is: [PATCH 3/3][NAND][OMAP] : Fixing issue in oamp nand driver in prefetch mode read Can you please give a look for this patch series?
On Mon, 2010-01-11 at 12:00 +0530, Vimal Singh wrote: > On Sun, Jan 10, 2010 at 2:16 PM, Artem Bityutskiy <dedekind1@gmail.com> wrote: > > On Thu, 2009-12-31 at 17:50 +0530, Vimal Singh wrote: > >> There is a bug in nand prefetch read routine, which comes into effect > >> only if nand device is a 16-bit device (as we have in zoom boards). > >> This bug is effective only with below combination of conditions: > >> 1. nand deivce, in use, is a 16 bit device > >> 2. nand driver supports 'subpage' read > >> 3. SW ECC is in use > >> > >> This was not seen old kernel (ex: .23), because when, in early days, > >> we tested this (nand prefetch read in LDP boards) there was no > >> 'subpage read' support. > >> Later when we had subpage read in (.27) kernel, we had hw ecc enabled > >> always in our internal tree. So, we missed this bug. > >> > >> Here is a patch to fix this issue: > >> > >> diff --git a/drivers/mtd/nand/omap2.c b/drivers/mtd/nand/omap2.c > >> index 1bb799f..75004fe 100644 > >> --- a/drivers/mtd/nand/omap2.c > >> +++ b/drivers/mtd/nand/omap2.c > >> @@ -295,11 +295,14 @@ static void omap_read_buf_pref(struct > >> u32 *p = (u32 *)buf; > >> > >> /* take care of subpage reads */ > >> - for (; len % 4 != 0; ) { > >> - *buf++ = __raw_readb(info->nand.IO_ADDR_R); > >> - len--; > >> + if (len % 4) { > >> + if (info->nand.options & NAND_BUSWIDTH_16) > >> + omap_read_buf16(mtd, buf, len % 4); > >> + else > >> + omap_read_buf8(mtd, buf, len % 4); > >> + p = (u32 *) (buf + len % 4); > >> + len -= len % 4; > >> } > >> - p = (u32 *) buf; > >> > >> /* configure and start prefetch transfer */ > >> ret = gpmc_prefetch_enable(info->gpmc_cs, 0x0, len, 0x0); > > > > Pushed this patch to my l2-mtd-2.6.git/dunno. > > > > I have posted this patch formally in patch series: > [PATCH 0/3][NAND][OMAP]: fixing omap nand driver issues > > Corresponding patch is: > [PATCH 3/3][NAND][OMAP] : Fixing issue in oamp nand driver in prefetch mode read > > Can you please give a look for this patch series? Just pushed them to my l2-mtd-2.6.git/dunno
diff --git a/drivers/mtd/nand/omap2.c b/drivers/mtd/nand/omap2.c index 1bb799f..75004fe 100644 --- a/drivers/mtd/nand/omap2.c +++ b/drivers/mtd/nand/omap2.c @@ -295,11 +295,14 @@ static void omap_read_buf_pref(struct u32 *p = (u32 *)buf; /* take care of subpage reads */ - for (; len % 4 != 0; ) { - *buf++ = __raw_readb(info->nand.IO_ADDR_R); - len--; + if (len % 4) { + if (info->nand.options & NAND_BUSWIDTH_16) + omap_read_buf16(mtd, buf, len % 4); + else + omap_read_buf8(mtd, buf, len % 4); + p = (u32 *) (buf + len % 4); + len -= len % 4; } - p = (u32 *) buf; /* configure and start prefetch transfer */ ret = gpmc_prefetch_enable(info->gpmc_cs, 0x0, len, 0x0);