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Re: [PATCH V2 1/3] scsi: mptxsas: try 64 bit DMA when 32 bit DMA fails

From Hannes Reinecke <hare@suse.de>
Newsgroups linux.kernel
Subject Re: [PATCH V2 1/3] scsi: mptxsas: try 64 bit DMA when 32 bit DMA fails
Date 2015-11-09 08:20 +0100
Message-ID <qsOU9-3hO-1@gated-at.bofh.it> (permalink)
References <qsJUu-88f-9@gated-at.bofh.it> <qsJUv-88f-15@gated-at.bofh.it>
Organization linux.* mail to news gateway

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On 11/09/2015 02:57 AM, Sinan Kaya wrote:
> Current code gives up when 32 bit DMA is not supported.
> This problem has been observed on systems without any
> memory below 4 gig.
> 
> This patch tests 64 bit support before bailing out to find
> a working combination.
> 
That feels decidedly odd.

Why do you probe for 64bit if 32bit fails?
Typically it's the other way round, on the grounds that 64bit DMA
should be preferred over 32bit.
Can you explain why it needs to be done the other way round here?

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		               zSeries & Storage
hare@suse.de			               +49 911 74053 688
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: F. Imendörffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton
HRB 21284 (AG Nürnberg)
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Thread

[PATCH V2 1/3] scsi: mptxsas: try 64 bit DMA when 32 bit DMA fails Sinan Kaya <okaya@codeaurora.org> - 2015-11-09 03:00 +0100
  Re: [PATCH V2 1/3] scsi: mptxsas: try 64 bit DMA when 32 bit DMA  fails Hannes Reinecke <hare@suse.de> - 2015-11-09 08:20 +0100
    Re: [PATCH V2 1/3] scsi: mptxsas: try 64 bit DMA when 32 bit DMA fails Arnd Bergmann <arnd@arndb.de> - 2015-11-09 10:10 +0100
      Re: [PATCH V2 1/3] scsi: mptxsas: try 64 bit DMA when 32 bit DMA  fails Sinan Kaya <okaya@codeaurora.org> - 2015-11-09 15:10 +0100
        Re: [PATCH V2 1/3] scsi: mptxsas: try 64 bit DMA when 32 bit DMA fails Arnd Bergmann <arnd@arndb.de> - 2015-11-09 15:40 +0100
          Re: [PATCH V2 1/3] scsi: mptxsas: try 64 bit DMA when 32 bit DMA  fails Timur Tabi <timur@codeaurora.org> - 2015-11-10 00:30 +0100
          Re: [PATCH V2 1/3] scsi: mptxsas: try 64 bit DMA when 32 bit DMA  fails Sinan Kaya <okaya@codeaurora.org> - 2015-11-10 00:30 +0100
            Re: [PATCH V2 1/3] scsi: mptxsas: try 64 bit DMA when 32 bit DMA fails Arnd Bergmann <arnd@arndb.de> - 2015-11-10 09:50 +0100
              Re: [PATCH V2 1/3] scsi: mptxsas: try 64 bit DMA when 32 bit DMA  fails Sinan Kaya <okaya@codeaurora.org> - 2015-11-10 17:10 +0100
                Re: [PATCH V2 1/3] scsi: mptxsas: try 64 bit DMA when 32 bit DMA fails Arnd Bergmann <arnd@arndb.de> - 2015-11-10 17:50 +0100
                Re: [PATCH V2 1/3] scsi: mptxsas: try 64 bit DMA when 32 bit DMA  fails Timur Tabi <timur@codeaurora.org> - 2015-11-10 18:10 +0100
                Re: [PATCH V2 1/3] scsi: mptxsas: try 64 bit DMA when 32 bit DMA fails Arnd Bergmann <arnd@arndb.de> - 2015-11-10 20:20 +0100
                Re: [PATCH V2 1/3] scsi: mptxsas: try 64 bit DMA when 32 bit DMA  fails Timur Tabi <timur@codeaurora.org> - 2015-11-10 22:10 +0100
                Re: [PATCH V2 1/3] scsi: mptxsas: try 64 bit DMA when 32 bit DMA  fails Timur Tabi <timur@codeaurora.org> - 2015-11-10 23:00 +0100
                Re: [PATCH V2 1/3] scsi: mptxsas: try 64 bit DMA when 32 bit DMA fails Arnd Bergmann <arnd@arndb.de> - 2015-11-10 23:10 +0100
                Re: [PATCH V2 1/3] scsi: mptxsas: try 64 bit DMA when 32 bit DMA fails Arnd Bergmann <arnd@arndb.de> - 2015-11-10 23:00 +0100
                Re: [PATCH V2 1/3] scsi: mptxsas: try 64 bit DMA when 32 bit DMA  fails Sinan Kaya <okaya@codeaurora.org> - 2015-11-10 18:20 +0100
                Re: [PATCH V2 1/3] scsi: mptxsas: try 64 bit DMA when 32 bit DMA  fails James Bottomley <James.Bottomley@HansenPartnership.com> - 2015-11-10 19:30 +0100
                Re: [PATCH V2 1/3] scsi: mptxsas: try 64 bit DMA when 32 bit DMA  fails Sinan Kaya <okaya@codeaurora.org> - 2015-11-10 20:20 +0100
                Re: [PATCH V2 1/3] scsi: mptxsas: try 64 bit DMA when 32 bit DMA  fails James Bottomley <James.Bottomley@HansenPartnership.com> - 2015-11-10 20:50 +0100
                Re: [PATCH V2 1/3] scsi: mptxsas: try 64 bit DMA when 32 bit DMA  fails Sinan Kaya <okaya@codeaurora.org> - 2015-11-10 21:00 +0100
                Re: [PATCH V2 1/3] scsi: mptxsas: try 64 bit DMA when 32 bit DMA  fails James Bottomley <James.Bottomley@HansenPartnership.com> - 2015-11-10 21:10 +0100
                Re: [PATCH V2 1/3] scsi: mptxsas: try 64 bit DMA when 32 bit DMA  fails Sinan Kaya <okaya@codeaurora.org> - 2015-11-10 21:30 +0100
                Re: [PATCH V2 1/3] scsi: mptxsas: try 64 bit DMA when 32 bit DMA  fails James Bottomley <James.Bottomley@HansenPartnership.com> - 2015-11-10 21:40 +0100
                Re: [PATCH V2 1/3] scsi: mptxsas: try 64 bit DMA when 32 bit DMA fails Arnd Bergmann <arnd@arndb.de> - 2015-11-10 21:00 +0100
                Re: [PATCH V2 1/3] scsi: mptxsas: try 64 bit DMA when 32 bit DMA  fails Sinan Kaya <okaya@codeaurora.org> - 2015-11-10 22:00 +0100
                Re: [PATCH V2 1/3] scsi: mptxsas: try 64 bit DMA when 32 bit DMA fails Arnd Bergmann <arnd@arndb.de> - 2015-11-10 23:10 +0100
    Re: [PATCH V2 1/3] scsi: mptxsas: try 64 bit DMA when 32 bit DMA  fails Sinan Kaya <okaya@codeaurora.org> - 2015-11-09 15:10 +0100

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