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SubjectRe: [PATCH] mtd: nand: denali: allow to override max_banks from DT property
On Thu, 24 Mar 2016 21:24:37 +0900
Masahiro Yamada <yamada.masahiro@socionext.com> wrote:

> Commit 271707b1d817 ("mtd: nand: denali: max_banks calculation
> changed in revision 5.1") supported the new encoding of the "n_banks"
> bits of the "features" register, but there is an unfortunate case
> that is not covered by that commit.
>
> Panasonic (its System LSI division is now Socionext) bought several
> versions of this IP. The IP released for Panasonic around Feb. 2012
> is revision 5 and uses the old encoding for n_banks (2 << n_banks).
> While the one released around Nov. 2012 is also revision 5, but it
> uses the new encoding (1 << n_banks).
>
> The revision register cannot distinguish these two incompatible
> hardware. I guess this IP series is not well-organized. I could not
> find any alternative but giving max_banks from DT property.

Hm, shouldn't that be addressed with a new compatible instead of adding
a extra property?

>
> This commit works around the problem by allowing DT to set the
> max_banks forcibly. Of course, this DT property can be optional if
> the auto detection based on the hardware registers works well.
>
> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
> ---
>
> Documentation/devicetree/bindings/mtd/denali-nand.txt | 4 ++++
> drivers/mtd/nand/denali.c | 3 ++-
> drivers/mtd/nand/denali_dt.c | 3 +++
> 3 files changed, 9 insertions(+), 1 deletion(-)
>
> diff --git a/Documentation/devicetree/bindings/mtd/denali-nand.txt b/Documentation/devicetree/bindings/mtd/denali-nand.txt
> index 785b825..78c250d 100644
> --- a/Documentation/devicetree/bindings/mtd/denali-nand.txt
> +++ b/Documentation/devicetree/bindings/mtd/denali-nand.txt
> @@ -7,6 +7,10 @@ Required properties:
> - interrupts : The interrupt number.
> - dma-mask : DMA bit mask
>
> +Optional properties:
> + - max-banks : Maximum number of banks supported by hardware. If not
> + specified, it is determined based on the "features" register of hardware.
> +

You might want to prefix that with "denali,".

> The device tree may optionally contain sub-nodes describing partitions of the
> address space. See partition.txt for more detail.
>
> diff --git a/drivers/mtd/nand/denali.c b/drivers/mtd/nand/denali.c
> index 30bf5f6..e18b569 100644
> --- a/drivers/mtd/nand/denali.c
> +++ b/drivers/mtd/nand/denali.c
> @@ -1353,7 +1353,8 @@ static void denali_hw_init(struct denali_nand_info *denali)
> */
> denali->bbtskipbytes = ioread32(denali->flash_reg +
> SPARE_AREA_SKIP_BYTES);
> - detect_max_banks(denali);
> + if (!denali->max_banks)
> + detect_max_banks(denali);
> denali_nand_reset(denali);
> iowrite32(0x0F, denali->flash_reg + RB_PIN_ENABLED);
> iowrite32(CHIP_EN_DONT_CARE__FLAG,
> diff --git a/drivers/mtd/nand/denali_dt.c b/drivers/mtd/nand/denali_dt.c
> index 0cb1e8d..be55db8 100644
> --- a/drivers/mtd/nand/denali_dt.c
> +++ b/drivers/mtd/nand/denali_dt.c
> @@ -85,6 +85,9 @@ static int denali_dt_probe(struct platform_device *ofdev)
> denali->dev->dma_mask = NULL;
> }
>
> + of_property_read_u32(ofdev->dev.of_node, "max-banks",
> + &denali->max_banks);
> +
> dt->clk = devm_clk_get(&ofdev->dev, NULL);
> if (IS_ERR(dt->clk)) {
> dev_err(&ofdev->dev, "no clk available\n");



--
Boris Brezillon, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com

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