Scott Wood a écrit :
> On 08/22/2011 10:25 AM, Ivan Djelic wrote:
>> Did you take into account the fact that because MTD thinks this a 2K chip,
>> you will have to wait twice for the nand busy read time (typically 25 us) per
>> each 4K read. In other words, to read 4 kBytes you will do:
>>
>> 1. send read0 (00), send address, send read1 (30)
>> 2. wait tRB
>> 3. transfer 2 kBytes
>> 4. send read0 (00), send address, send read1 (30)
>> 5. wait tRB
>> 6. transfer 2 kBytes
>>
>> Same problem for writes (but rather 100 us instead of 25 us).
>>
>> How does that compare with hw ecc gain in terms of performance ?
>
> We'd have the double-delay with the sw ecc plus buffering approach as well.
>
> To eliminate it we'd need to do an extra data transfer without reissuing
> the command, which Shuo was unable to get to work.
>
That's weird because our controller seems quite flexible [1].
Something like that should work ?
out_be32(&lbc->fir,
(FIR_OP_CM2 << FIR_OP0_SHIFT) |
(FIR_OP_CA << FIR_OP1_SHIFT) |
(FIR_OP_PA << FIR_OP2_SHIFT) |
(FIR_OP_WB << FIR_OP3_SHIFT));
refill FCM buffer with next 2k data
out_be32(&lbc->fir,
(FIR_OP_WB << FIR_OP3_SHIFT) |
(FIR_OP_CM3 << FIR_OP4_SHIFT) |
(FIR_OP_CW1 << FIR_OP5_SHIFT) |
(FIR_OP_RS << FIR_OP6_SHIFT));
[1]
__be32 fir; /**< Flash Instruction Register */
#define FIR_OP0 0xF0000000
#define FIR_OP0_SHIFT 28
#define FIR_OP1 0x0F000000
#define FIR_OP1_SHIFT 24
#define FIR_OP2 0x00F00000
#define FIR_OP2_SHIFT 20
#define FIR_OP3 0x000F0000
#define FIR_OP3_SHIFT 16
#define FIR_OP4 0x0000F000
#define FIR_OP4_SHIFT 12
#define FIR_OP5 0x00000F00
#define FIR_OP5_SHIFT 8
#define FIR_OP6 0x000000F0
#define FIR_OP6_SHIFT 4
#define FIR_OP7 0x0000000F
#define FIR_OP7_SHIFT 0
#define FIR_OP_NOP 0x0 /* No operation and end of sequence */
#define FIR_OP_CA 0x1 /* Issue current column address */
#define FIR_OP_PA 0x2 /* Issue current block+page address */
#define FIR_OP_UA 0x3 /* Issue user defined address */
#define FIR_OP_CM0 0x4 /* Issue command from FCR[CMD0] */
#define FIR_OP_CM1 0x5 /* Issue command from FCR[CMD1] */
#define FIR_OP_CM2 0x6 /* Issue command from FCR[CMD2] */
#define FIR_OP_CM3 0x7 /* Issue command from FCR[CMD3] */
#define FIR_OP_WB 0x8 /* Write FBCR bytes from FCM buffer */
#define FIR_OP_WS 0x9 /* Write 1 or 2 bytes from MDR[AS] */
#define FIR_OP_RB 0xA /* Read FBCR bytes to FCM buffer */
#define FIR_OP_RS 0xB /* Read 1 or 2 bytes to MDR[AS] */
#define FIR_OP_CW0 0xC /* Wait then issue FCR[CMD0] */
#define FIR_OP_CW1 0xD /* Wait then issue FCR[CMD1] */
#define FIR_OP_RBW 0xE /* Wait then read FBCR bytes */
#define FIR_OP_RSW 0xE /* Wait then read 1 or 2 bytes */
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