[U-Boot] [PATCH u-boot-spi 1/1] spi: mvebu_a3700_spi: Fix clock prescale computation
The prescaler value computation can yield wrong result if given 0x1f at the beginning: the value is computed to be 0x20, but the maximum value the register can hold 0x1f, so the actual stored value in this case is 0, which is obviously wrong. The first condition should also take care of the 0x1f value.
Signed-off-by: Marek Behún marek.behun@nic.cz --- drivers/spi/mvebu_a3700_spi.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/spi/mvebu_a3700_spi.c b/drivers/spi/mvebu_a3700_spi.c index feeafdceaa..cc73ff3fee 100644 --- a/drivers/spi/mvebu_a3700_spi.c +++ b/drivers/spi/mvebu_a3700_spi.c @@ -181,7 +181,7 @@ static int mvebu_spi_set_speed(struct udevice *bus, uint hz) data = readl(®->cfg);
prescale = DIV_ROUND_UP(clk_get_rate(&plat->clk), hz); - if (prescale > 0x1f) + if (prescale >= 0x1f) prescale = 0x1f; else if (prescale > 0xf) prescale = 0x10 + (prescale + 1) / 2;
On 17.07.19 16:58, Marek Behún wrote:
The prescaler value computation can yield wrong result if given 0x1f at the beginning: the value is computed to be 0x20, but the maximum value the register can hold 0x1f, so the actual stored value in this case is 0, which is obviously wrong. The first condition should also take care of the 0x1f value.
Wouldn't it be better to max the value after the calculation (see below)...
Signed-off-by: Marek Behún marek.behun@nic.cz
drivers/spi/mvebu_a3700_spi.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/spi/mvebu_a3700_spi.c b/drivers/spi/mvebu_a3700_spi.c index feeafdceaa..cc73ff3fee 100644 --- a/drivers/spi/mvebu_a3700_spi.c +++ b/drivers/spi/mvebu_a3700_spi.c @@ -181,7 +181,7 @@ static int mvebu_spi_set_speed(struct udevice *bus, uint hz) data = readl(®->cfg);
prescale = DIV_ROUND_UP(clk_get_rate(&plat->clk), hz);
- if (prescale > 0x1f)
- if (prescale >= 0x1f) prescale = 0x1f; else if (prescale > 0xf) prescale = 0x10 + (prescale + 1) / 2;
Something like this:
if (prescale > 0xf) prescale = 0x10 + (prescale + 1) / 2; prescale = min(prescale, 0x1f);
?
Thanks, Stefan
:) probably yes
On Wed, 17 Jul 2019 18:21:35 +0200 Stefan Roese sr@denx.de wrote:
On 17.07.19 16:58, Marek Behún wrote:
The prescaler value computation can yield wrong result if given 0x1f at the beginning: the value is computed to be 0x20, but the maximum value the register can hold 0x1f, so the actual stored value in this case is 0, which is obviously wrong. The first condition should also take care of the 0x1f value.
Wouldn't it be better to max the value after the calculation (see below)...
Signed-off-by: Marek Behún marek.behun@nic.cz
drivers/spi/mvebu_a3700_spi.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/spi/mvebu_a3700_spi.c b/drivers/spi/mvebu_a3700_spi.c index feeafdceaa..cc73ff3fee 100644 --- a/drivers/spi/mvebu_a3700_spi.c +++ b/drivers/spi/mvebu_a3700_spi.c @@ -181,7 +181,7 @@ static int mvebu_spi_set_speed(struct udevice *bus, uint hz) data = readl(®->cfg);
prescale = DIV_ROUND_UP(clk_get_rate(&plat->clk), hz);
- if (prescale > 0x1f)
- if (prescale >= 0x1f) prescale = 0x1f; else if (prescale > 0xf) prescale = 0x10 + (prescale + 1) / 2;
Something like this:
if (prescale > 0xf) prescale = 0x10 + (prescale + 1) / 2; prescale = min(prescale, 0x1f);
?
Thanks, Stefan
participants (2)
-
Marek Behún -
Stefan Roese