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SubjectRe: [PATCH 07/14] qcom: mtd: nand: support for passing flags in transfer functions
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Hi,

On 7/4/2017 12:19 PM, Archit Taneja wrote:
>
>
> On 06/29/2017 12:45 PM, Abhishek Sahu wrote:
>> The BAM has multiple flags to control the transfer. This patch
>> adds flags parameter in register and data transfer functions and
>> modifies all these function call with appropriate flags.
>>
>> Signed-off-by: Abhishek Sahu <absahu@codeaurora.org>
>> ---
>> drivers/mtd/nand/qcom_nandc.c | 114 ++++++++++++++++++++++++------------------
>> 1 file changed, 65 insertions(+), 49 deletions(-)
>>
>> diff --git a/drivers/mtd/nand/qcom_nandc.c b/drivers/mtd/nand/qcom_nandc.c
>> index 7042a65..65c9059 100644
>> --- a/drivers/mtd/nand/qcom_nandc.c
>> +++ b/drivers/mtd/nand/qcom_nandc.c
>> @@ -170,6 +170,14 @@
>> #define ECC_BCH_4BIT BIT(2)
>> #define ECC_BCH_8BIT BIT(3)
>> +/* Flags used for BAM DMA desc preparation*/
>> +/* Don't set the EOT in current tx sgl */
>> +#define NAND_BAM_NO_EOT (0x0001)
>> +/* Set the NWD flag in current sgl */
>> +#define NAND_BAM_NWD (0x0002)
>> +/* Finish writing in the current sgl and start writing in another sgl */
>> +#define NAND_BAM_NEXT_SGL (0x0004)
>> +
>> #define QPIC_PER_CW_MAX_CMD_ELEMENTS (32)
>> #define QPIC_PER_CW_MAX_CMD_SGL (32)
>> #define QPIC_PER_CW_MAX_DATA_SGL (8)
>> @@ -712,7 +720,7 @@ static int prep_dma_desc(struct qcom_nand_controller *nandc, bool read,
>> * @num_regs: number of registers to read
>> */
>> static int read_reg_dma(struct qcom_nand_controller *nandc, int first,
>> - int num_regs)
>> + int num_regs, unsigned int flags)
>> {
>> bool flow_control = false;
>> void *vaddr;
>> @@ -736,7 +744,7 @@ static int read_reg_dma(struct qcom_nand_controller *nandc, int first,
>> * @num_regs: number of registers to write
>> */
>> static int write_reg_dma(struct qcom_nand_controller *nandc, int first,
>> - int num_regs)
>> + int num_regs, unsigned int flags)
>
> Adding flags to read_reg_dma and write_reg_dma is making things a bit messy. I can't
> think of a better way to share the code either, though.
>
> One thing we could consider doing is something like below. I don't know if it would
> make things more legible.
>
> union nand_dma_props {
> bool adm_flow_control;
> unsigned int bam_flags;
> };
>
> config_cw_read()
> {
> union nand_dma_props dma_props;
> ...
> ...
>
> if (is_bam)
> dma_props.bam_flags = NAND_BAM_NWD;
> else
> dma_props.adm_flow_control = false;
>
> write_reg_dma(nandc, NAND_EXEC_CMD, 1, &dma_props);
> ...
> ...
> }

Right, with this , i think we can have two different indirections for functions like,
prep_dma_desc_command and prep_dma_desc. That will help to reduce the bam_dma_enabled
checks.

Regards,
Sricharan

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