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SubjectRe: [PATCH 1/3] ARM: OMAP2+: gpmc: Fix writing in gpmc_cs_set_memconf
On 24/01/15 22:28, Semen Protsenko wrote:
> Some GPMC_CONFIG7 register bits marked as "RESERVED", means they
> shouldn't be overwritten. A typical approach to handle such bits called
> "Read-Modify-Write". Writing procedure used in gpmc_cs_set_memconf()
> utilizes RMW technique, but implemented incorrectly. Due to obvious typo
> in code read register value is being rewritten by another value, which
> leads to loss of read RESERVED bits. This patch fixes this.
>
> While at it, replace magic numbers with named constants to improve code
> readability.
>
> Signed-off-by: Semen Protsenko <semen.protsenko@globallogic.com>

This is much nicer.

Acked-by: Roger Quadros <rogerq@ti.com>

cheers,
-roger

> ---
> drivers/memory/omap-gpmc.c | 20 ++++++++++++++++----
> 1 file changed, 16 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/memory/omap-gpmc.c b/drivers/memory/omap-gpmc.c
> index 24696f5..10eb4ac 100644
> --- a/drivers/memory/omap-gpmc.c
> +++ b/drivers/memory/omap-gpmc.c
> @@ -153,6 +153,15 @@
> #define GPMC_CONFIG1_FCLK_DIV4 (GPMC_CONFIG1_FCLK_DIV(3))
> #define GPMC_CONFIG7_CSVALID (1 << 6)
>
> +#define GPMC_CONFIG7_BASEADDRESS_MASK 0x3f
> +#define GPMC_CONFIG7_CSVALID_MASK BIT(6)
> +#define GPMC_CONFIG7_MASKADDRESS_OFFSET 8
> +#define GPMC_CONFIG7_MASKADDRESS_MASK (0xf << GPMC_CONFIG7_MASKADDRESS_OFFSET)
> +/* All CONFIG7 bits except reserved bits */
> +#define GPMC_CONFIG7_MASK (GPMC_CONFIG7_BASEADDRESS_MASK | \
> + GPMC_CONFIG7_CSVALID_MASK | \
> + GPMC_CONFIG7_MASKADDRESS_MASK)
> +
> #define GPMC_DEVICETYPE_NOR 0
> #define GPMC_DEVICETYPE_NAND 2
> #define GPMC_CONFIG_WRITEPROTECT 0x00000010
> @@ -586,12 +595,15 @@ static int gpmc_cs_set_memconf(int cs, u32 base, u32 size)
> if (base & (size - 1))
> return -EINVAL;
>
> + base >>= GPMC_CHUNK_SHIFT;
> mask = (1 << GPMC_SECTION_SHIFT) - size;
> + mask >>= GPMC_CHUNK_SHIFT;
> + mask <<= GPMC_CONFIG7_MASKADDRESS_OFFSET;
> +
> l = gpmc_cs_read_reg(cs, GPMC_CS_CONFIG7);
> - l &= ~0x3f;
> - l = (base >> GPMC_CHUNK_SHIFT) & 0x3f;
> - l &= ~(0x0f << 8);
> - l |= ((mask >> GPMC_CHUNK_SHIFT) & 0x0f) << 8;
> + l &= ~GPMC_CONFIG7_MASK;
> + l |= base & GPMC_CONFIG7_BASEADDRESS_MASK;
> + l |= mask & GPMC_CONFIG7_MASKADDRESS_MASK;
> l |= GPMC_CONFIG7_CSVALID;
> gpmc_cs_write_reg(cs, GPMC_CS_CONFIG7, l);
>
>



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