Re: [PATCH v2 2/2] spi: spi-ti-qspi: Use bounce buffer if read buffer is not DMA'ble

From	Vignesh R <vigneshr@ti.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH v2 2/2] spi: spi-ti-qspi: Use bounce buffer if read buffer is not DMA'ble
Date	2017-04-25 14:20 +0200
Message-ID	<tA7BL-4B0-3@gated-at.bofh.it> (permalink)
References	<tv2CK-6tD-7@gated-at.bofh.it> <tv2CK-6tD-17@gated-at.bofh.it> <tyLDm-LM-67@gated-at.bofh.it>
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On Friday 21 April 2017 10:36 PM, Mark Brown wrote:
> On Tue, Apr 11, 2017 at 05:22:25PM +0530, Vignesh R wrote:
>> Flash filesystems like JFFS2, UBIFS and MTD block layer can provide
>> vmalloc'd or kmap'd buffers that cannot be mapped using dma_map_sg() and
>> can potentially be in memory region above 32bit addressable region(ie
>> buffers belonging to memory region backed by LPAE) of DMA, implement
>> spi_flash_can_dma() interface to inform SPI core not to map such
>> buffers.
> 
> I'll apply this since it fixes bugs for your systems but it feels like
> something that we should be moving further into the core since LPAE
> isn't specific to your devices.  We should ideally have something
> (possibly in the DMA mapping code even) which does the remapping without
> the driver needing to know about it.
> 

I agree, there is a need to have generic remapping code. Also, I guess,
once UBIFS is moved to use kmalloc'd buffers SPI flash devices will not
have to worry much about vmalloc'd buffers.

-- 
Regards
Vignesh

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[PATCH v2 0/2] spi-ti-qspi: Handle vmalloc'd buffers Vignesh R <vigneshr@ti.com> - 2017-04-11 14:00 +0200
  [PATCH v2 2/2] spi: spi-ti-qspi: Use bounce buffer if read buffer is not DMA'ble Vignesh R <vigneshr@ti.com> - 2017-04-11 14:00 +0200
    Applied "spi: spi-ti-qspi: Use bounce buffer if read buffer is not DMA'ble" to the spi tree Mark Brown <broonie@kernel.org> - 2017-04-21 20:30 +0200
    Re: [PATCH v2 2/2] spi: spi-ti-qspi: Use bounce buffer if read  buffer is not DMA'ble Mark Brown <broonie@kernel.org> - 2017-04-21 20:40 +0200
      Re: [PATCH v2 2/2] spi: spi-ti-qspi: Use bounce buffer if read buffer  is not DMA'ble Vignesh R <vigneshr@ti.com> - 2017-04-25 14:20 +0200

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