linux-kernel - Re: [PATCH v3 3/9] misc: sram: use phys_addr

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Date:	Tue, 19 May 2015 15:30:06 +0300
From:	Vladimir Zapolskiy <vladimir_zapolskiy@...tor.com>
To:	Philipp Zabel <p.zabel@...gutronix.de>
CC:	Heiko Stübner <heiko@...ech.de>,
	Arnd Bergmann <arnd@...db.de>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 3/9] misc: sram: use phys_addr_t instead of u32 for
 physical address

Hi Philipp,

thank you for review.

On 19.05.2015 13:38, Philipp Zabel wrote:
> Hi Vladimir,
> 
> Am Montag, den 18.05.2015, 22:08 +0300 schrieb Vladimir Zapolskiy:
>> To avoid any problems on non 32-bit platforms get and store memory
>> addresses under phys_addr_t type.
>>
>> Signed-off-by: Vladimir Zapolskiy <vladimir_zapolskiy@...tor.com>
>> ---
>> Changes from v1 to v2:
>> - report size of SRAM in decimal format '%zu' instead of '%zx'
>> - replacement of denominator '1024' to SZ_1K requires explicit
>>   include of linux/sizes.h on some platforms, keep it as a number
>>
>>  drivers/misc/sram.c | 26 +++++++++++++++-----------
>>  1 file changed, 15 insertions(+), 11 deletions(-)
>>
>> diff --git a/drivers/misc/sram.c b/drivers/misc/sram.c
>> index 999684a..b7a3a24 100644
>> --- a/drivers/misc/sram.c
>> +++ b/drivers/misc/sram.c
>> @@ -41,8 +41,8 @@ struct sram_dev {
>>  
>>  struct sram_reserve {
>>  	struct list_head list;
>> -	u32 start;
>> -	u32 size;
>> +	phys_addr_t start;
>> +	size_t size;
>>  };
>>  
>>  static int sram_reserve_cmp(void *priv, struct list_head *a,
>> @@ -60,7 +60,8 @@ static int sram_probe(struct platform_device *pdev)
>>  	struct sram_dev *sram;
>>  	struct resource *res;
>>  	struct device_node *np = pdev->dev.of_node, *child;
>> -	unsigned long size, cur_start, cur_size;
>> +	phys_addr_t cur_start;
>> +	size_t size, cur_size;
>>  	struct sram_reserve *rblocks, *block;
>>  	struct list_head reserve_list;
>>  	unsigned int nblocks;
>> @@ -138,9 +139,9 @@ static int sram_probe(struct platform_device *pdev)
>>  		block->size = resource_size(&child_res);
>>  		list_add_tail(&block->list, &reserve_list);
>>  
>> -		dev_dbg(&pdev->dev, "found reserved block 0x%x-0x%x\n",
>> -			block->start,
>> -			block->start + block->size);
>> +		dev_dbg(&pdev->dev, "found reserved block 0x%llx-0x%llx\n",
>> +			(unsigned long long)block->start,
> 
> Now that block->start is of type phys_addr_t, is there a reason not to
> use %pa ?

the only reason why I decided not to use %pa in the change is because
the value should be passed over a pointer then.

For instance right here it is possible to change '"0x%llx", (unsigned
long long)block->start' to '"%pa", &block->start', however some lines
below the same trick can not be done for '(unsigned long long)cur_start
+ cur_size' value. Among alternatives to introduce a local variable, use
mixed "0x%llx" and "%pa" or use unified "0x%llx" I selected the latter one.

>> +			(unsigned long long)block->start + block->size);
> 
> 		phys_addr_t end = block->start + block->size;
> 
> 		dev_dbg(&pdev->dev, "found reserved block 0x%pa-0x%pa\n",
> 			&block->start, &end);
>  
>>  		block++;
>>  	}
>> @@ -158,8 +159,9 @@ static int sram_probe(struct platform_device *pdev)
>>  		/* can only happen if sections overlap */
>>  		if (block->start < cur_start) {
>>  			dev_err(&pdev->dev,
>> -				"block at 0x%x starts after current offset 0x%lx\n",
>> -				block->start, cur_start);
>> +				"block at 0x%llx starts after current offset 0x%llx\n",
>> +				(unsigned long long)block->start,
>> +				(unsigned long long)cur_start);
> 
> 			dev_err(&pdev->dev,
> 				"block at 0x%pa starts after current offset 0x%pa\n",
> 				&block->start, &cur_start);
> 
>>  			ret = -EINVAL;
>>  			goto err_chunks;
>>  		}
>> @@ -177,8 +179,9 @@ static int sram_probe(struct platform_device *pdev)
>>  		 */
>>  		cur_size = block->start - cur_start;
>>  
>> -		dev_dbg(&pdev->dev, "adding chunk 0x%lx-0x%lx\n",
>> -			cur_start, cur_start + cur_size);
>> +		dev_dbg(&pdev->dev, "adding chunk 0x%llx-0x%llx\n",
>> +			(unsigned long long)cur_start,
>> +			(unsigned long long)cur_start + cur_size);
> 
> 		dev_dbg(&pdev->dev, "adding chunk 0x%pa-0x%pa\n",
> 			&cur_start, &block->start);
> 
>>  		ret = gen_pool_add_virt(sram->pool,
>>  				(unsigned long)virt_base + cur_start,
>>  				res->start + cur_start, cur_size, -1);
>> @@ -193,7 +196,8 @@ static int sram_probe(struct platform_device *pdev)
>>  
>>  	platform_set_drvdata(pdev, sram);
>>  
>> -	dev_dbg(&pdev->dev, "SRAM pool: %ld KiB @ 0x%p\n", size / 1024, virt_base);
>> +	dev_dbg(&pdev->dev, "SRAM pool: %zu KiB @ 0x%p\n",
>> +		size / 1024, virt_base);
>>  
>>  	return 0;
> 
> regards
> Philipp
> 

--
With best wishes,
Vladimir
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