On 10/16/22 07:46, Heinrich Schuchardt wrote:
On 10/16/22 09:51, Michal Suchánek wrote:
On Thu, Oct 13, 2022 at 10:34:29PM +0200, Michal Suchanek wrote:
k210 is 64bit but the driver and tests are also built in sandbox, and that can be built 32bit.
BIT(32) does not work on 32bit, shift before subtraction to fit into 32bit integer with BIT values.
Also see https://patchwork.ozlabs.org/project/uboot/patch/20221016071035.461454-1-hei...
Signed-off-by: Michal Suchanek msuchanek@suse.de
drivers/clk/clk_k210.c | 2 +- test/dm/k210_pll.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/clk/clk_k210.c b/drivers/clk/clk_k210.c index 1961efaa5e..e85f8ae14a 100644 --- a/drivers/clk/clk_k210.c +++ b/drivers/clk/clk_k210.c @@ -846,7 +846,7 @@ again: error = DIV_ROUND_CLOSEST_ULL(f * inv_ratio, r * od); /* The lower 16 bits are spurious */ - error = abs((error - BIT(32))) >> 16; + error = abs((error >> 16) - BIT(32 - 16));
Your patch changes the results. Replacing BIT() by BIT_ULL() does not change the result:
error = -1 = 0xffffffffffffffff before error - BIT(32) = -4294967297 = 0xfffffffeffffffff abs(error - BIT(32)) = 4294967297 = 0x100000001 abs(error - BIT(32)) >> 16 = 65536 = 0x10000 after error >> 16 = -1 = 0xffffffffffffffff (error >> 16) - BIT(32 - 16) = -65537 = 0xfffffffffffeffff abs((error >> 16) - BIT(32 - 16)) = 65537 = 0x10001 using BIT_ULL abs(error - BIT_ULL(32)) >> 16 = 65536 = 0x10000
error = 70000 = 0x11170 before error - BIT(32) = -4294897296 = 0xffffffff00011170 abs(error - BIT(32)) = 4294897296 = 0xfffeee90 abs(error - BIT(32)) >> 16 = 65534 = 0xfffe after error >> 16 = 1 = 0x1 (error >> 16) - BIT(32 - 16) = -65535 = 0xffffffffffff0001 abs((error >> 16) - BIT(32 - 16)) = 65535 = 0xffff using BIT_ULL abs(error - BIT_ULL(32)) >> 16 = 65534 = 0xfffe
I assume this change of results is unintended.
We also replace abs() by abs64() to get correct results on a 32bit system:
error = -1 = 0xffffffffffffffff abs(error - BIT_ULL(32)) >> 16 = 0 = 0x0 abs64(error - BIT_ULL(32)) >> 16 = 65536 = 0x10000 error = 70000 = 0x11170 abs(error - BIT_ULL(32)) >> 16 = 1 = 0x1 abs64(error - BIT_ULL(32)) >> 16 = 65534 = 0xfffe
Best regards
Heinrich
if (error < best_error) { best->r = r; diff --git a/test/dm/k210_pll.c b/test/dm/k210_pll.c index a0cc84c396..622b1c9bef 100644 --- a/test/dm/k210_pll.c +++ b/test/dm/k210_pll.c @@ -33,7 +33,7 @@ static int dm_test_k210_pll_calc_config(u32 rate, u32 rate_in, error = DIV_ROUND_CLOSEST_ULL(f * inv_ratio, r * od); /* The lower 16 bits are spurious */ - error = abs((error - BIT(32))) >> 16; + error = abs((error >> 16) - BIT(32 - 16)); if (error < best_error) { best->r = r; best->f = f; -- 2.37.3
IMO the driver should just be changed to depend on 64-bit. The k210 is 64-bit, and I didn't write anything with 32-bit in mind.
--Sean