2020-06-08 10:51:59

by Sivaprakash Murugesan

Subject: [PATCH] mtd: raw: qcom_nand: Fix register write error

1. SFLASHC_BURST_CFG register is not available on all ipq nand platforms,
it is available only on ipq8064 devices and the nand controller works
without configuring these registers in this platform, so register
write to this can be removed.

2. Once BAM mode is enabled register writes to NAND_CTRL should be
performed through BAM command descriptors. The NAND BAM mode will
be enabled by bootloaders. Check if BAM mode is already enabled and
enable it only if not enabled already.

Signed-off-by: Sivaprakash Murugesan <[email protected]>
---
drivers/mtd/nand/raw/qcom_nandc.c | 11 ++++++++---
1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/drivers/mtd/nand/raw/qcom_nandc.c b/drivers/mtd/nand/raw/qcom_nandc.c
index 5b11c70..7bfd93a 100644
--- a/drivers/mtd/nand/raw/qcom_nandc.c
+++ b/drivers/mtd/nand/raw/qcom_nandc.c
@@ -36,7 +36,6 @@
#define NAND_DEV_CMD1 0xa4
#define NAND_DEV_CMD2 0xa8
#define NAND_DEV_CMD_VLD 0xac
-#define SFLASHC_BURST_CFG 0xe0
#define NAND_ERASED_CW_DETECT_CFG 0xe8
#define NAND_ERASED_CW_DETECT_STATUS 0xec
#define NAND_EBI2_ECC_BUF_CFG 0xf0
@@ -2774,14 +2773,20 @@ 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, dev_cmd_reg_addr(nandc, NAND_DEV_CMD_VLD),
NAND_DEV_CMD_VLD_VAL);

/* 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);
+ /* Once BAM_MODE_EN bit is set, writes to the NAND_CTRL
+ * should be done through BAM command descriptors.
+ * in most cases bootloader enables the bam mode we
+ * need to set the BAM mode only if it is not set by
+ * bootloader
+ */
+ if (!(nand_ctrl & BAM_MODE_EN))
+ nandc_write(nandc, NAND_CTRL, nand_ctrl | BAM_MODE_EN);
} else {
nandc_write(nandc, NAND_FLASH_CHIP_SELECT, DM_EN);
}
--
2.7.4

2020-06-08 12:42:18

by Miquel Raynal

Subject: Re: [PATCH] mtd: raw: qcom_nand: Fix register write error

Hi Sivaprakash,

Sivaprakash Murugesan <[email protected]> wrote on Mon, 8 Jun
2020 16:17:34 +0530:

Subject prefix should be mtd: rawnand: qcom:

And I don't think "Fix register write error" is relevant in any of the
two following cases.

> 1. SFLASHC_BURST_CFG register is not available on all ipq nand platforms,
> it is available only on ipq8064 devices and the nand controller works
> without configuring these registers in this platform, so register
> write to this can be removed.
>
> 2. Once BAM mode is enabled register writes to NAND_CTRL should be
> performed through BAM command descriptors. The NAND BAM mode will
> be enabled by bootloaders. Check if BAM mode is already enabled and
> enable it only if not enabled already.
>

It looks like there are two completely different changes that you are
doing here, please split.

Also, please explain why #2 is needed, it is not very clear.

Thanks,
Miquèl

> Signed-off-by: Sivaprakash Murugesan <[email protected]>
> ---
> drivers/mtd/nand/raw/qcom_nandc.c | 11 ++++++++---
> 1 file changed, 8 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/mtd/nand/raw/qcom_nandc.c b/drivers/mtd/nand/raw/qcom_nandc.c
> index 5b11c70..7bfd93a 100644
> --- a/drivers/mtd/nand/raw/qcom_nandc.c
> +++ b/drivers/mtd/nand/raw/qcom_nandc.c
> @@ -36,7 +36,6 @@
> #define NAND_DEV_CMD1 0xa4
> #define NAND_DEV_CMD2 0xa8
> #define NAND_DEV_CMD_VLD 0xac
> -#define SFLASHC_BURST_CFG 0xe0
> #define NAND_ERASED_CW_DETECT_CFG 0xe8
> #define NAND_ERASED_CW_DETECT_STATUS 0xec
> #define NAND_EBI2_ECC_BUF_CFG 0xf0
> @@ -2774,14 +2773,20 @@ 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, dev_cmd_reg_addr(nandc, NAND_DEV_CMD_VLD),
> NAND_DEV_CMD_VLD_VAL);
>
> /* 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);
> + /* Once BAM_MODE_EN bit is set, writes to the NAND_CTRL
> + * should be done through BAM command descriptors.
> + * in most cases bootloader enables the bam mode we
> + * need to set the BAM mode only if it is not set by
> + * bootloader
> + */
> + if (!(nand_ctrl & BAM_MODE_EN))
> + nandc_write(nandc, NAND_CTRL, nand_ctrl | BAM_MODE_EN);
> } else {
> nandc_write(nandc, NAND_FLASH_CHIP_SELECT, DM_EN);
> }