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SubjectRe: [PATCH] Staging: olpc_dcon: replace some magic numbers
Please Cc Daniel on these.  Cjb and myself are no longer at olpc. 



On Sat, 3 Aug 2013 22:44:35 +0200
Jens Frederich <jfrederich@gmail.com> wrote:

> This patch replace some magic numbers. I believe it makes
> the driver more readable.
>
> The magic number 0x26 is the XO system embedded controller
> (EC) command 'DCON power enable/disable'.
>
> Number 0x41, and 0x42 are special memory controller settings
> register. The 0x41 initialize bit sequence 0x101 means:
> enable memory power down function and special SDRAM clock
> delay for synchronize SDRAM output and clock signal.
>
> The 0x42 initialize squence 0x101 is wrong. According to
> the specification Bit 8 is reserved, thus not in use.
> I removed it.
>
> Signed-off-by: Jens Frederich <jfrederich@gmail.com>
>
> diff --git a/drivers/staging/olpc_dcon/olpc_dcon.c
> b/drivers/staging/olpc_dcon/olpc_dcon.c index 7c460f2..5ca4fa4 100644
> --- a/drivers/staging/olpc_dcon/olpc_dcon.c
> +++ b/drivers/staging/olpc_dcon/olpc_dcon.c
> @@ -90,9 +90,10 @@ static int dcon_hw_init(struct dcon_priv *dcon,
> int is_init)
> /* SDRAM setup/hold time */
> dcon_write(dcon, 0x3a, 0xc040);
> - dcon_write(dcon, 0x41, 0x0000);
> - dcon_write(dcon, 0x41, 0x0101);
> - dcon_write(dcon, 0x42, 0x0101);
> + dcon_write(dcon, DCON_REG_MEM_OPT_A, 0x0000); /* clear
> option bits */
> + dcon_write(dcon, DCON_REG_MEM_OPT_A,
> + MEM_DLL_CLOCK_DELAY |
> MEM_POWER_DOWN);
> + dcon_write(dcon, DCON_REG_MEM_OPT_B, MEM_SOFT_RESET);
>
> /* Colour swizzle, AA, no passthrough, backlight */
> if (is_init) {
> @@ -126,7 +127,7 @@ static int dcon_bus_stabilize(struct dcon_priv
> *dcon, int is_powered_down) power_up:
> if (is_powered_down) {
> x = 1;
> - x = olpc_ec_cmd(0x26, (unsigned char *)&x, 1, NULL,
> 0);
> + x = olpc_ec_cmd(EC_DCON_POWER_MODE, (u8 *)&x, 1,
> NULL, 0); if (x) {
> pr_warn("unable to force dcon to power up:
> %d!\n", x); return x;
> @@ -144,7 +145,7 @@ power_up:
> pr_err("unable to stabilize dcon's smbus,
> reasserting power and praying.\n");
> BUG_ON(olpc_board_at_least(olpc_board(0xc2))); x = 0;
> - olpc_ec_cmd(0x26, (unsigned char *)&x, 1, NULL, 0);
> + olpc_ec_cmd(EC_DCON_POWER_MODE, (u8 *)&x, 1, NULL,
> 0); msleep(100);
> is_powered_down = 1;
> goto power_up; /* argh, stupid hardware.. */
> @@ -208,7 +209,7 @@ static void dcon_sleep(struct dcon_priv *dcon,
> bool sleep)
> if (sleep) {
> x = 0;
> - x = olpc_ec_cmd(0x26, (unsigned char *)&x, 1, NULL,
> 0);
> + x = olpc_ec_cmd(EC_DCON_POWER_MODE, (u8 *)&x, 1,
> NULL, 0); if (x)
> pr_warn("unable to force dcon to power down:
> %d!\n", x); else
> diff --git a/drivers/staging/olpc_dcon/olpc_dcon.h
> b/drivers/staging/olpc_dcon/olpc_dcon.h index 997bded..524ee49 100644
> --- a/drivers/staging/olpc_dcon/olpc_dcon.h
> +++ b/drivers/staging/olpc_dcon/olpc_dcon.h
> @@ -22,15 +22,24 @@
> #define MODE_DEBUG (1<<14)
> #define MODE_SELFTEST (1<<15)
>
> -#define DCON_REG_HRES 2
> -#define DCON_REG_HTOTAL 3
> -#define DCON_REG_HSYNC_WIDTH 4
> -#define DCON_REG_VRES 5
> -#define DCON_REG_VTOTAL 6
> -#define DCON_REG_VSYNC_WIDTH 7
> -#define DCON_REG_TIMEOUT 8
> -#define DCON_REG_SCAN_INT 9
> -#define DCON_REG_BRIGHT 10
> +#define DCON_REG_HRES 0x2
> +#define DCON_REG_HTOTAL 0x3
> +#define DCON_REG_HSYNC_WIDTH 0x4
> +#define DCON_REG_VRES 0x5
> +#define DCON_REG_VTOTAL 0x6
> +#define DCON_REG_VSYNC_WIDTH 0x7
> +#define DCON_REG_TIMEOUT 0x8
> +#define DCON_REG_SCAN_INT 0x9
> +#define DCON_REG_BRIGHT 0x10
> +#define DCON_REG_MEM_OPT_A 0x41
> +#define DCON_REG_MEM_OPT_B 0x42
> +
> +/* Load Delay Locked Loop (DLL) settings for clock delay */
> +#define MEM_DLL_CLOCK_DELAY (1<<0)
> +/* Memory controller power down function */
> +#define MEM_POWER_DOWN (1<<8)
> +/* Memory controller software reset */
> +#define MEM_SOFT_RESET (1<<0)
>
> /* Status values */
>
> diff --git a/include/linux/olpc-ec.h b/include/linux/olpc-ec.h
> index 5bb6e76..2925df3 100644
> --- a/include/linux/olpc-ec.h
> +++ b/include/linux/olpc-ec.h
> @@ -6,6 +6,7 @@
> #define EC_WRITE_SCI_MASK 0x1b
> #define EC_WAKE_UP_WLAN 0x24
> #define EC_WLAN_LEAVE_RESET 0x25
> +#define EC_DCON_POWER_MODE 0x26
> #define EC_READ_EB_MODE 0x2a
> #define EC_SET_SCI_INHIBIT 0x32
> #define EC_SET_SCI_INHIBIT_RELEASE 0x34


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