linux-kernel - Re: [PATCH] fsldma: fsl_ioread64*() do not need lower_32

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Message-ID: <dc4491f8-f74c-c3c4-82c4-3986c5352205@csgroup.eu>
Date:   Sat, 29 Aug 2020 17:58:24 +0200
From:   Christophe Leroy <christophe.leroy@...roup.eu>
To:     Guenter Roeck <linux@...ck-us.net>,
        Luc Van Oostenryck <luc.vanoostenryck@...il.com>
Cc:     Herbert Xu <herbert@...dor.apana.org.au>,
        Joerg Roedel <joerg.roedel@....com>,
        linuxppc-dev@...ts.ozlabs.org, Li Yang <leoyang.li@....com>,
        Zhang Wei <zw@...kernel.org>, Vinod Koul <vkoul@...nel.org>,
        dmaengine@...r.kernel.org,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Dan Williams <dan.j.williams@...el.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] fsldma: fsl_ioread64*() do not need lower_32_bits()



Le 29/08/2020 à 17:05, Guenter Roeck a écrit :
> On Sat, Aug 29, 2020 at 02:45:38PM +0200, Luc Van Oostenryck wrote:
>> For ppc32, the functions fsl_ioread64() & fsl_ioread64be()
>> use lower_32_bits() as a fancy way to cast the pointer to u32
>> in order to do non-atomic 64-bit IO.
>>
>> But the pointer is already 32-bit, so simply cast the pointer to u32.
>>
>> This fixes a compile error introduced by
>>     ef91bb196b0d ("kernel.h: Silence sparse warning in lower_32_bits")
>>
>> Fixes: ef91bb196b0db1013ef8705367bc2d7944ef696b
> 
> checkpatch complains about this and prefers
> 
> Fixes: ef91bb196b0d ("kernel.h: Silence sparse warning in lower_32_bits")

Checkpatch also complains about spacing:

CHECK:SPACING: No space is necessary after a cast
#39: FILE: drivers/dma/fsldma.h:208:
+	u32 fsl_addr = (u32) addr;

CHECK:SPACING: No space is necessary after a cast
#48: FILE: drivers/dma/fsldma.h:222:
+	u32 fsl_addr = (u32) addr;

total: 0 errors, 0 warnings, 2 checks, 16 lines checked

Christophe

> 
> Otherwise
> 
> Tested-by: Guenter Roeck <linux@...ck-us.net>
> 
>> Reported-by: Guenter Roeck <linux@...ck-us.net>
>> Cc: Li Yang <leoyang.li@....com>
>> Cc: Zhang Wei <zw@...kernel.org>
>> Cc: Dan Williams <dan.j.williams@...el.com>
>> Cc: Vinod Koul <vkoul@...nel.org>
>> Cc: Herbert Xu <herbert@...dor.apana.org.au>
>> Cc: linuxppc-dev@...ts.ozlabs.org
>> Cc: dmaengine@...r.kernel.org
>> Cc: linux-kernel@...r.kernel.org
>> Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@...il.com>
>> ---
>>   drivers/dma/fsldma.h | 4 ++--
>>   1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/dma/fsldma.h b/drivers/dma/fsldma.h
>> index 56f18ae99233..6f6fa7641fa2 100644
>> --- a/drivers/dma/fsldma.h
>> +++ b/drivers/dma/fsldma.h
>> @@ -205,7 +205,7 @@ struct fsldma_chan {
>>   #else
>>   static u64 fsl_ioread64(const u64 __iomem *addr)
>>   {
>> -	u32 fsl_addr = lower_32_bits(addr);
>> +	u32 fsl_addr = (u32) addr;
>>   	u64 fsl_addr_hi = (u64)in_le32((u32 *)(fsl_addr + 1)) << 32;
>>   
>>   	return fsl_addr_hi | in_le32((u32 *)fsl_addr);
>> @@ -219,7 +219,7 @@ static void fsl_iowrite64(u64 val, u64 __iomem *addr)
>>   
>>   static u64 fsl_ioread64be(const u64 __iomem *addr)
>>   {
>> -	u32 fsl_addr = lower_32_bits(addr);
>> +	u32 fsl_addr = (u32) addr;
>>   	u64 fsl_addr_hi = (u64)in_be32((u32 *)fsl_addr) << 32;
>>   
>>   	return fsl_addr_hi | in_be32((u32 *)(fsl_addr + 1));
>> -- 
>> 2.28.0
>>