Re: [U-Boot] [PATCH 10/19] mtd: nand: pxa3xx_nand: add support for partial chunks
On 29.08.2018 10:56, kos...@marvell.com wrote:
From: Ofer Heifetz
This commit is needed to properly support the 8-bits ECC configuration
with 4KB pages.
When pages larger than 2 KB are used on platforms using the PXA3xx
NAND controller, the reading/programming operations need to be split
in chunks of 2 KBs or less because the controller FIFO is limited to
about 2 KB (i.e a bit more than 2 KB to accommodate OOB data). Due to
this requirement, the data layout on NAND is a bit strange, with ECC
interleaved with data, at the end of each chunk.
When a 4-bits ECC configuration is used with 4 KB pages, the physical
data layout on the NAND looks like this:
| 2048 data | 32 spare | 30 ECC | 2048 data | 32 spare | 30 ECC |
So the data chunks have an equal size, 2080 bytes for each chunk,
which the driver supports properly.
When a 8-bits ECC configuration is used with 4KB pages, the physical
data layout on the NAND looks like this:
| 1024 data | 30 ECC | 1024 data | 30 ECC | 1024 data | 30 ECC | 1024 data | 30
ECC | 64 spare | 30 ECC |
So, the spare area is stored in its own chunk, which has a different
size than the other chunks. Since OOB is not used by UBIFS, the initial
implementation of the driver has chosen to not support reading this
additional "spare" chunk of data.
Unfortunately, Marvell has chosen to store the BBT signature in the
OOB area. Therefore, if the driver doesn't read this spare area, Linux
has no way of finding the BBT. It thinks there is no BBT, and rewrites
one, which U-Boot does not recognize, causing compatibility problems
between the bootloader and the kernel in terms of NAND usage.
To fix this, this commit implements the support for reading a partial
last chunk. This support is currently only useful for the case of 8
bits ECC with 4 KB pages, but it will be useful in the future to
enable other configurations such as 12 bits and 16 bits ECC with 4 KB
pages, or 8 bits ECC with 8 KB pages, etc. All those configurations
have a "last" chunk that doesn't have the same size as the other
chunks.
In order to implement reading of the last chunk, this commit:
- Adds a number of new fields to the pxa3xx_nand_info to describe how
many full chunks and how many chunks we have, the size of full
chunks and partial chunks, both in terms of data area and spare
area.
- Fills in the step_chunk_size and step_spare_size variables to
describe how much data and spare should be read/written for the
current read/program step.
- Reworks the state machine to accommodate doing the additional read
or program step when a last partial chunk is used.
This commit is taken from Linux:
'commit c2cdace755b'
("mtd: nand: pxa3xx_nand: add support for partial chunks")
Signed-off-by: Chris Packham
Signed-off-by: Ofer Heifetz
Reviewed-by: Igal Liberman
Cc: Stefan Roese
Cc: Simon Glass
---
drivers/mtd/nand/pxa3xx_nand.c | 154 ++---
1 file changed, 99 insertions(+), 55 deletions(-)
diff --git a/drivers/mtd/nand/pxa3xx_nand.c b/drivers/mtd/nand/pxa3xx_nand.c
index 4faf787..5cc75de 100644
--- a/drivers/mtd/nand/pxa3xx_nand.c
+++ b/drivers/mtd/nand/pxa3xx_nand.c
@@ -201,15 +201,44 @@ struct pxa3xx_nand_info {
int use_spare; /* use spare ? */
int need_wait;
- unsigned int data_size; /* data to be read from FIFO */
- unsigned intchunk_size; /* split commands chunk size */
- unsigned intoob_size;
+ /* Amount of real data per full chunk */
+ unsigned intchunk_size;
+
+ /* Amount of spare data per full chunk */
unsigned intspare_size;
+
+ /* Number of full chunks (i.e chunk_size + spare_size) */
+ unsigned intnfullchunks;
+
+ /*
+* Total number of chunks. If equal to nfullchunks, then there
+* are only full chunks. Otherwise, there is one last chunk of
+* size (last_chunk_size + last_spare_size)
+*/
+ unsigned intntotalchunks;
+
+ /* Amount of real data in the last chunk */
+ unsigned intlast_chunk_size;
+
+ /* Amount of spare data in the last chunk */
+ unsigned intlast_spare_size;
+
unsigned intecc_size;
unsigned intecc_err_cnt;
unsigned intmax_bitflips;
int retcode;
+ /*
+* Variables only valid during command
+* execution. step_chunk_size and step_spare_size is the
+* amount of real data and spare data in the current
+* chunk. cur_chunk is the current chunk being
+* read/programmed.
+*/
+ unsigned intstep_chunk_size;
+ unsigned intstep_spare_size;
+ unsigned intcur_chunk;
+
/* cached register value */
uint32_treg_ndcr;
uint32_t
[U-Boot] [PATCH 10/19] mtd: nand: pxa3xx_nand: add support for partial chunks
From: Ofer Heifetz
This commit is needed to properly support the 8-bits ECC configuration
with 4KB pages.
When pages larger than 2 KB are used on platforms using the PXA3xx
NAND controller, the reading/programming operations need to be split
in chunks of 2 KBs or less because the controller FIFO is limited to
about 2 KB (i.e a bit more than 2 KB to accommodate OOB data). Due to
this requirement, the data layout on NAND is a bit strange, with ECC
interleaved with data, at the end of each chunk.
When a 4-bits ECC configuration is used with 4 KB pages, the physical
data layout on the NAND looks like this:
| 2048 data | 32 spare | 30 ECC | 2048 data | 32 spare | 30 ECC |
So the data chunks have an equal size, 2080 bytes for each chunk,
which the driver supports properly.
When a 8-bits ECC configuration is used with 4KB pages, the physical
data layout on the NAND looks like this:
| 1024 data | 30 ECC | 1024 data | 30 ECC | 1024 data | 30 ECC | 1024 data | 30
ECC | 64 spare | 30 ECC |
So, the spare area is stored in its own chunk, which has a different
size than the other chunks. Since OOB is not used by UBIFS, the initial
implementation of the driver has chosen to not support reading this
additional "spare" chunk of data.
Unfortunately, Marvell has chosen to store the BBT signature in the
OOB area. Therefore, if the driver doesn't read this spare area, Linux
has no way of finding the BBT. It thinks there is no BBT, and rewrites
one, which U-Boot does not recognize, causing compatibility problems
between the bootloader and the kernel in terms of NAND usage.
To fix this, this commit implements the support for reading a partial
last chunk. This support is currently only useful for the case of 8
bits ECC with 4 KB pages, but it will be useful in the future to
enable other configurations such as 12 bits and 16 bits ECC with 4 KB
pages, or 8 bits ECC with 8 KB pages, etc. All those configurations
have a "last" chunk that doesn't have the same size as the other
chunks.
In order to implement reading of the last chunk, this commit:
- Adds a number of new fields to the pxa3xx_nand_info to describe how
many full chunks and how many chunks we have, the size of full
chunks and partial chunks, both in terms of data area and spare
area.
- Fills in the step_chunk_size and step_spare_size variables to
describe how much data and spare should be read/written for the
current read/program step.
- Reworks the state machine to accommodate doing the additional read
or program step when a last partial chunk is used.
This commit is taken from Linux:
'commit c2cdace755b'
("mtd: nand: pxa3xx_nand: add support for partial chunks")
Signed-off-by: Chris Packham
Signed-off-by: Ofer Heifetz
Reviewed-by: Igal Liberman
Cc: Stefan Roese
Cc: Simon Glass
---
drivers/mtd/nand/pxa3xx_nand.c | 154 ++---
1 file changed, 99 insertions(+), 55 deletions(-)
diff --git a/drivers/mtd/nand/pxa3xx_nand.c b/drivers/mtd/nand/pxa3xx_nand.c
index 4faf787..5cc75de 100644
--- a/drivers/mtd/nand/pxa3xx_nand.c
+++ b/drivers/mtd/nand/pxa3xx_nand.c
@@ -201,15 +201,44 @@ struct pxa3xx_nand_info {
int use_spare; /* use spare ? */
int need_wait;
- unsigned intdata_size; /* data to be read from FIFO */
- unsigned intchunk_size; /* split commands chunk size */
- unsigned intoob_size;
+ /* Amount of real data per full chunk */
+ unsigned intchunk_size;
+
+ /* Amount of spare data per full chunk */
unsigned intspare_size;
+
+ /* Number of full chunks (i.e chunk_size + spare_size) */
+ unsigned intnfullchunks;
+
+ /*
+* Total number of chunks. If equal to nfullchunks, then there
+* are only full chunks. Otherwise, there is one last chunk of
+* size (last_chunk_size + last_spare_size)
+*/
+ unsigned intntotalchunks;
+
+ /* Amount of real data in the last chunk */
+ unsigned intlast_chunk_size;
+
+ /* Amount of spare data in the last chunk */
+ unsigned intlast_spare_size;
+
unsigned intecc_size;
unsigned intecc_err_cnt;
unsigned intmax_bitflips;
int retcode;
+ /*
+* Variables only valid during command
+* execution. step_chunk_size and step_spare_size is the
+* amount of real data and spare data in the current
+* chunk. cur_chunk is the current chunk being
+* read/programmed.
+*/
+ unsigned intstep_chunk_size;
+ unsigned intstep_spare_size;
+ unsigned intcur_chunk;
+
/* cached register value */
uint32_treg_ndcr;
uint32_tndtr0cs0;
@@ -436,25 +465,6 @@
