Re: [PATCH V3 2/4] soc/tegra: pmc: Correct type of variable for tegra_pmc_readl()

From: Laxman Dewangan
Date: Thu May 05 2016 - 08:47:29 EST

On Thursday 05 May 2016 06:13 PM, Jon Hunter wrote:
On 05/05/16 10:52, Laxman Dewangan wrote:
On Thursday 05 May 2016 03:19 PM, Jon Hunter wrote:
On 04/05/16 12:39, Laxman Dewangan wrote:
The function tegra_pmc_readl() returns the u32 type data and hence
change the data type of variable where this data is stored to u32

Signed-off-by: Laxman Dewangan <ldewangan@xxxxxxxxxx>

Changes from V1:
-This is new in series as per discussion on V1 series to use u32 for

Changes from V2:
- Make unsigned long to u32 for some missed variable from V1.
drivers/soc/tegra/pmc.c | 24 ++++++++++++++----------
1 file changed, 14 insertions(+), 10 deletions(-)

diff --git a/drivers/soc/tegra/pmc.c b/drivers/soc/tegra/pmc.c
index 2c3f1f9..eff9425 100644
--- a/drivers/soc/tegra/pmc.c
+++ b/drivers/soc/tegra/pmc.c
@@ -844,7 +844,8 @@ static void tegra_powergate_init(struct tegra_pmc
static int tegra_io_rail_prepare(unsigned int id, unsigned long
unsigned long *status, unsigned int *bit)
- unsigned long rate, value;
+ unsigned long rate;
+ u32 value;
*bit = id % 32;
@@ -868,17 +869,18 @@ static int tegra_io_rail_prepare(unsigned int
id, unsigned long *request,
tegra_pmc_writel(DPD_SAMPLE_ENABLE, DPD_SAMPLE);
/* must be at least 200 ns, in APB (PCLK) clock cycles */
- value = DIV_ROUND_UP(1000000000, rate);
- value = DIV_ROUND_UP(200, value);
+ rate = DIV_ROUND_UP(1000000000, rate);
+ rate = DIV_ROUND_UP(200, rate);
+ value = (u32)rate;
Although it is unlikely, I think that we should check it is less
than U32_MAX, return an error if it is not.
rate = DIV_ROUNC_UP(200, rate) means

rate = (200 + rate -1)/rate

and can not be more than 200 in any case (if rate =1).
So no need of the error check.
OK, yes you are right. In that case there is no need to cast and so I
would leave this code as-is and not change the type.

You mean keep value as unsigned long for value?

I think we can still say value as u32 and simply write
value = rate

Just remove the casting.