From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jon Hunter Subject: Re: [PATCH V3 2/4] soc/tegra: pmc: Correct type of variable for tegra_pmc_readl() Date: Thu, 5 May 2016 13:48:38 +0100 Message-ID: <572B4126.30008@nvidia.com> References: <1462361973-27990-1-git-send-email-ldewangan@nvidia.com> <1462361973-27990-3-git-send-email-ldewangan@nvidia.com> <572B173D.6030108@nvidia.com> <572B17DA.901@nvidia.com> <572B3FF9.8080202@nvidia.com> <572B3DFB.3070604@nvidia.com> Mime-Version: 1.0 Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <572B3DFB.3070604-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org> Sender: linux-tegra-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Laxman Dewangan , thierry.reding-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, swarren-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org, airlied-cv59FeDIM0c@public.gmane.org Cc: gnurou-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, dri-devel-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org, linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-tegra@vger.kernel.org On 05/05/16 13:35, Laxman Dewangan wrote: > > 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 >>>>> type. >>>>> >>>>> Signed-off-by: Laxman Dewangan >>>>> >>>>> --- >>>>> Changes from V1: >>>>> -This is new in series as per discussion on V1 series to use u32 for >>>>> tegra_pmc_readl. >>>>> >>>>> 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 >>>>> *pmc) >>>>> static int tegra_io_rail_prepare(unsigned int id, unsigned long >>>>> *request, >>>>> 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? Yes. > I think we can still say value as u32 and simply write > value = rate > > Just remove the casting. I would not change this at all. I don't see any benefit. Jon