[U-Boot] [PATCH] arm: mvebu: a38x: Weed out floating point use

Marek Vasut
2016-05-19T23:46:49Z

On 04/30/2016 02:45 PM, Marek Vasut wrote:
> For reason unknown, recently, the DDR init code writers are really fond
> of hiding some small floating point operating deep in their creations.
> This patch removes one from the Marvell A38x code.
>
> Instead of returning size of chip as float from ddr3_get_device_size()
> in GiB units, return it as int in MiB units. Since this would interfere
> with the huge switch code in ddr3_calc_mem_cs_size(), rework the code
> to match the change.
>
> Before this patch, the cs_mem_size variable could have these values:
> ( { 16, 32 } x { 8, 16 } x { 0.01, 0.5, 1, 2, 4, 8 } ) / 8 =
> { 0.000000, 0.001250, 0.002500, 0.005000, 0.062500, 0.125000,
> 0.250000, 0.500000, 1.000000, 2.000000, 4.000000, }
> The switch code checked for a subset of the resulting RAM sizes, which
> is in range 128 MiB ... 2048 MiB.
>
> With this patch, the cs_mem_size variable can have these values:
> ( { 16, 32 } x { 8, 16 } x { 0, 512, 1024, 2048, 4096, 8192 } ) / 8 =
> { 0, 64, 128, 256, 512, 1024, 2048, 4096 }
> To retain previous behavior, filter out 0 MiB (invalid size), 64 MiB
> and 4096 MiB options.
>
> Removing the floating point stuff also saves 1.5k from text segment:
> clearfog : spl/u-boot-spl:all -1592 spl/u-boot-spl:text -1592
>
> Signed-off-by: Marek Vasut <marex@denx.de>
> Cc: Dirk Eibach <dirk.eibach@gdsys.cc>
> Cc: Stefan Roese <sr@denx.de>

Bump?

> ---
> drivers/ddr/marvell/a38x/ddr3_init.c | 29 ++++++++++-------------------
> 1 file changed, 10 insertions(+), 19 deletions(-)
>
> diff --git a/drivers/ddr/marvell/a38x/ddr3_init.c b/drivers/ddr/marvell/a38x/ddr3_init.c
> index ee05f57..55baad4 100644
> --- a/drivers/ddr/marvell/a38x/ddr3_init.c
> +++ b/drivers/ddr/marvell/a38x/ddr3_init.c
> @@ -678,7 +678,7 @@ u32 ddr3_get_device_width(u32 cs)
> return (device_width == 0) ? 8 : 16;
> }
>
> -float ddr3_get_device_size(u32 cs)
> +static int ddr3_get_device_size(u32 cs)
> {
> u32 device_size_low, device_size_high, device_size;
> u32 data, cs_low_offset, cs_high_offset;
> @@ -695,15 +695,15 @@ float ddr3_get_device_size(u32 cs)
>
> switch (device_size) {
> case 0:
> - return 2;
> + return 2048;
> case 2:
> - return 0.5;
> + return 512;
> case 3:
> - return 1;
> + return 1024;
> case 4:
> - return 4;
> + return 4096;
> case 5:
> - return 8;
> + return 8192;
> case 1:
> default:
> DEBUG_INIT_C("Error: Wrong device size of Cs: ", cs, 1);
> @@ -711,13 +711,13 @@ float ddr3_get_device_size(u32 cs)
> * Small value will give wrong emem size in
> * ddr3_calc_mem_cs_size
> */
> - return 0.01;
> + return 0;
> }
> }
>
> int ddr3_calc_mem_cs_size(u32 cs, u32 *cs_size)
> {
> - float cs_mem_size;
> + int cs_mem_size;
>
> /* Calculate in GiB */
> cs_mem_size = ((ddr3_get_bus_width() / ddr3_get_device_width(cs)) *
> @@ -731,21 +731,12 @@ int ddr3_calc_mem_cs_size(u32 cs, u32 *cs_size)
> */
> cs_mem_size *= DDR_CONTROLLER_BUS_WIDTH_MULTIPLIER;
>
> - if (cs_mem_size == 0.125) {
> - *cs_size = 128 << 20;
> - } else if (cs_mem_size == 0.25) {
> - *cs_size = 256 << 20;
> - } else if (cs_mem_size == 0.5) {
> - *cs_size = 512 << 20;
> - } else if (cs_mem_size == 1) {
> - *cs_size = 1 << 30;
> - } else if (cs_mem_size == 2) {
> - *cs_size = 2 << 30;
> - } else {
> + if (!cs_mem_size || (cs_mem_size == 64) || (cs_mem_size == 4096)) {
> DEBUG_INIT_C("Error: Wrong Memory size of Cs: ", cs, 1);
> return MV_BAD_VALUE;
> }
>
> + *cs_size = cs_mem_size << 20;
> return MV_OK;
> }
>
>