linux-kernel - Re: [PATCH v4 1/2] clk: hisilicon: Use correct return value about hisi_reset

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Date:   Thu, 28 May 2020 10:27:42 +0800
From:   Tiezhu Yang <yangtiezhu@...ngson.cn>
To:     Stephen Boyd <sboyd@...nel.org>,
        Michael Turquette <mturquette@...libre.com>
Cc:     linux-clk@...r.kernel.org, linux-kernel@...r.kernel.org,
        Xuefeng Li <lixuefeng@...ngson.cn>
Subject: Re: [PATCH v4 1/2] clk: hisilicon: Use correct return value about
 hisi_reset_init()

On 05/28/2020 03:06 AM, Stephen Boyd wrote:
> Quoting Tiezhu Yang (2020-05-27 07:39:21)
>> The return value about hisi_reset_init() is not correct, fix it.
>>
>> Fixes: e9a2310fb689 ("reset: hisilicon: fix potential NULL pointer dereference")
> hisi_reset_init() returns NULL on error in that commit. This patch
> doesn't make sense.

Hi Stephen,

The initial aim of this patch is to use correct return value about
hisi_reset_init(), maybe NULL is OK, but the return value in this
patch is more accurate.

In the current code, it always returns -ENOMEM when call function
hisi_reset_init() failed which is not proper, because in the function
hisi_reset_init(), devm_platform_ioremap_resource() may returns -EINVAL,
-EBUSY or -ENOMEM if failed.

devm_platform_ioremap_resource()
         devm_ioremap_resource()
                 __devm_ioremap_resource()


static void __iomem *
__devm_ioremap_resource(struct device *dev, const struct resource *res,
             enum devm_ioremap_type type)
{
     resource_size_t size;
     void __iomem *dest_ptr;

     BUG_ON(!dev);

     if (!res || resource_type(res) != IORESOURCE_MEM) {
         dev_err(dev, "invalid resource\n");
         return IOMEM_ERR_PTR(-EINVAL);
     }

     size = resource_size(res);

     if (!devm_request_mem_region(dev, res->start, size, dev_name(dev))) {
         dev_err(dev, "can't request region for resource %pR\n", res);
         return IOMEM_ERR_PTR(-EBUSY);
     }

     dest_ptr = __devm_ioremap(dev, res->start, size, type);
     if (!dest_ptr) {
         dev_err(dev, "ioremap failed for resource %pR\n", res);
         devm_release_mem_region(dev, res->start, size);
         dest_ptr = IOMEM_ERR_PTR(-ENOMEM);
     }

     return dest_ptr;
}

Thanks,
Tiezhu Yang

>
>> Signed-off-by: Tiezhu Yang <yangtiezhu@...ngson.cn>
>> ---
>>