Re: [PATCH v4 11/20] mtd: nand: qcom: enable BAM or ADM mode

Abhishek Sahu
2017-08-16T08:49:05Z

On 2017-08-16 10:20, Archit Taneja wrote:
> On 08/11/2017 05:09 PM, Abhishek Sahu wrote:
>> 1. DM_EN is only required for EBI2 NAND controller which uses ADM
>> 2. BAM mode will be disabled after power on reset which needs to
>> be enabled before starting any BAM transfers.
>>
>> Signed-off-by: Abhishek Sahu <absahu@codeaurora.org>
>> ---
>> drivers/mtd/nand/qcom_nandc.c | 17 ++++++++++++++---
>> 1 file changed, 14 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/mtd/nand/qcom_nandc.c
>> b/drivers/mtd/nand/qcom_nandc.c
>> index 3d9fd7f..ae873d3 100644
>> --- a/drivers/mtd/nand/qcom_nandc.c
>> +++ b/drivers/mtd/nand/qcom_nandc.c
>> @@ -163,6 +163,9 @@
>> #define NAND_DEV_CMD_VLD_VAL (READ_START_VLD | WRITE_START_VLD | \
>> ERASE_START_VLD | SEQ_READ_START_VLD)
>> +/* NAND_CTRL bits */
>> +#define BAM_MODE_EN BIT(0)
>> +
>> /*
>> * the NAND controller performs reads/writes with ECC in 516 byte
>> chunks.
>> * the driver calls the chunks 'step' or 'codeword' interchangeably
>> @@ -1035,7 +1038,8 @@ static int read_id(struct qcom_nand_host *host,
>> int column)
>> nandc_set_reg(nandc, NAND_FLASH_CMD, FETCH_ID);
>> nandc_set_reg(nandc, NAND_ADDR0, column);
>> nandc_set_reg(nandc, NAND_ADDR1, 0);
>> - nandc_set_reg(nandc, NAND_FLASH_CHIP_SELECT, DM_EN);
>> + nandc_set_reg(nandc, NAND_FLASH_CHIP_SELECT,
>> + nandc->props->is_bam ? 0 : DM_EN);
>
> I'm not sure why the above register was configured in read_id in the
> first place. Would
> it be required later if we want the controller to support multiple
> NAND chips? If not,
> then we could consider dropping this. Anyway, that can be posted as a
> separate patch
> later.

Correct. It seems the current driver does not have fully support
second NAND chip select since it need to program NAND_DEV1_CFG1 and
NAND_DEV1_CFG0 also.

We can have separate patch series which will add the full support
for multiple NAND chips and this line can be removed in that patch
series.

>
> Reviewed-by: Archit Taneja <architt@codeaurora.org>
>
> Thanks,
> Archit
>
>> nandc_set_reg(nandc, NAND_EXEC_CMD, 1);
>> write_reg_dma(nandc, NAND_FLASH_CMD, 4, NAND_BAM_NEXT_SGL);
>> @@ -2408,12 +2412,19 @@ static void qcom_nandc_unalloc(struct
>> qcom_nand_controller *nandc)
>> /* one time setup of a few nand controller registers */
>> static int qcom_nandc_setup(struct qcom_nand_controller *nandc)
>> {
>> + u32 nand_ctrl;
>> +
>> /* kill onenand */
>> nandc_write(nandc, SFLASHC_BURST_CFG, 0);
>> nandc_write(nandc, NAND_DEV_CMD_VLD, NAND_DEV_CMD_VLD_VAL);
>> - /* enable ADM DMA */
>> - nandc_write(nandc, NAND_FLASH_CHIP_SELECT, DM_EN);
>> + /* enable ADM or BAM DMA */
>> + if (nandc->props->is_bam) {
>> + nand_ctrl = nandc_read(nandc, NAND_CTRL);
>> + nandc_write(nandc, NAND_CTRL, nand_ctrl | BAM_MODE_EN);
>> + } else {
>> + nandc_write(nandc, NAND_FLASH_CHIP_SELECT, DM_EN);
>> + }
>> /* save the original values of these registers */
>> nandc->cmd1 = nandc_read(nandc, NAND_DEV_CMD1);
>>