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Re: [PATCH 1/5] mtd: nand: omap2: Support parsing dma channel information from DT

From "Franklin S Cooper Jr." <fcooper@ti.com>
Newsgroups linux.kernel
Subject Re: [PATCH 1/5] mtd: nand: omap2: Support parsing dma channel information from DT
Date 2015-10-14 22:10 +0200
Message-ID <qjAx3-CQ-1@gated-at.bofh.it> (permalink)
References (5 earlier) <qjv4o-Wf-45@gated-at.bofh.it> <qjvnH-1lp-15@gated-at.bofh.it> <qjwWt-3Le-7@gated-at.bofh.it> <qjx6a-3XF-13@gated-at.bofh.it> <qjyOD-6ut-19@gated-at.bofh.it>
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On 10/14/2015 01:13 PM, Tony Lindgren wrote:
> * Franklin S Cooper Jr. <fcooper@ti.com> [151014 09:27]:
>>
>> On 10/14/2015 11:18 AM, Tony Lindgren wrote:
>>> * Franklin S Cooper Jr. <fcooper@ti.com> [151014 07:37]:
>>>> On 10/14/2015 09:11 AM, Roger Quadros wrote:
>>>>> On 14/10/15 16:26, Franklin S Cooper Jr. wrote:
>>>>>> On 10/14/2015 06:52 AM, Roger Quadros wrote:
>>>>>>> Franklin,
>>>>>>>
>>>>>>> On 14/10/15 14:36, Roger Quadros wrote:
>>>>>>>> On 13/10/15 04:38, Franklin S Cooper Jr wrote:
>>>>>>>>> Switch from dma_request_channel to allow passing dma channel
>>>>>>>>> information from DT rather than hardcoding a value.
>>>>>>>>>
>>>>>>>>> Signed-off-by: Franklin S Cooper Jr <fcooper@ti.com>
>>>>>>>> Acked-by: Roger Quadros <rogerq@ti.com>
>>>>>>>>
>>>>>>>>> ---
>>>>>>>>>  drivers/mtd/nand/omap2.c | 4 +++-
>>>>>>>>>  1 file changed, 3 insertions(+), 1 deletion(-)
>>>>>>>>>
>>>>>>>>> diff --git a/drivers/mtd/nand/omap2.c b/drivers/mtd/nand/omap2.c
>>>>>>>>> index d0f2620..957c32f 100644
>>>>>>>>> --- a/drivers/mtd/nand/omap2.c
>>>>>>>>> +++ b/drivers/mtd/nand/omap2.c
>>>>>>>>> @@ -1866,7 +1866,9 @@ static int omap_nand_probe(struct platform_device *pdev)
>>>>>>>>>  		dma_cap_zero(mask);
>>>>>>>>>  		dma_cap_set(DMA_SLAVE, mask);
>>>>>>>>>  		sig = OMAP24XX_DMA_GPMC;
>>>>>>>>> -		info->dma = dma_request_channel(mask, omap_dma_filter_fn, &sig);
>>>>>>>>> +		info->dma = dma_request_slave_channel_compat(mask,
>>>>>>>>> +			omap_dma_filter_fn, &sig, pdev->dev.parent, "rxtx");
>>>>>>>>> +
>>>>>>> Just discovered that you are using the parent device node.
>>>>>>>
>>>>>>> How about moving the dma bindings to the nand node instead and using
>>>>>>> pdev->dev here?
>>>>>> Roger,
>>>>>>
>>>>>> From what I can tell the interrupt number and the dma channel will always be
>>>>>> the same no matter what. Doesn't matter if you have multiple nands or a
>>>>>> combination of nands and nors. Since that is the case I think it just makes
>>>>>> sense to leave it in the gpmc parent node and define it once.
>>>>> Is prefetch/writepost dma used for NOR or any other GPMC peripheral
>>>>> or only for NAND?
>>>> The dma seems tied to the prefetch. From what I can tell the prefetch is only
>>>> used by nand.
>>>>> Let's also get Tony's inputs on this.
>>>> Sure.
>>> Hmm so what would keep other devices from using the prefetch
>> Looking at the TRM any references to the prefetch are always with respect to
>> NAND.
>>
>> I also see the below mentioned in the TRM.
>> Pre-fetch and write posting engine associated with system DMA to get full performance from NAND
>> device with minimum impact on NOR/SRAM concurrent access.
> OK up to you guys to figure out if it may be usable in a generic way then :)
Ok I just got clarification from hw folks. DMA for GPMC can be used for any of the
various modes. But the prefetch is specific to NAND.
>
> Regards,
>
> Tony

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Thread

[PATCH 0/5] mtd: nand: Fix support for NAND DMA Prefetch  Franklin S Cooper Jr <fcooper@ti.com> - 2015-10-13 03:40 +0200
  [PATCH 3/5] mtd: nand: omap2: Fix high memory dma prefetch transfer Franklin S Cooper Jr <fcooper@ti.com> - 2015-10-13 03:40 +0200
  [PATCH 5/5] ARM: OMAP2+: Update gpmc and nand DT binding documentation Franklin S Cooper Jr <fcooper@ti.com> - 2015-10-13 03:40 +0200
    Re: [PATCH 5/5] ARM: OMAP2+: Update gpmc and nand DT binding  documentation Roger Quadros <rogerq@ti.com> - 2015-10-14 14:00 +0200
      Re: [PATCH 5/5] ARM: OMAP2+: Update gpmc and nand DT binding  documentation "Franklin S Cooper Jr." <fcooper@ti.com> - 2015-10-15 19:20 +0200
  [PATCH 4/5] ARM: dts: am437x/am33xx/omap3/dm816x: Add gpmc dma channel Franklin S Cooper Jr <fcooper@ti.com> - 2015-10-13 03:40 +0200
    Re: [PATCH 4/5] ARM: dts: am437x/am33xx/omap3/dm816x: Add gpmc dma  channel Roger Quadros <rogerq@ti.com> - 2015-10-14 13:50 +0200
      Re: [PATCH 4/5] ARM: dts: am437x/am33xx/omap3/dm816x: Add gpmc dma  channel "Franklin S Cooper Jr." <fcooper@ti.com> - 2015-10-14 16:00 +0200
  [PATCH 2/5] mtd: nand: omap2: Start dma request before enabling prefetch Franklin S Cooper Jr <fcooper@ti.com> - 2015-10-13 03:50 +0200
    Re: [PATCH 2/5] mtd: nand: omap2: Start dma request before enabling  prefetch Roger Quadros <rogerq@ti.com> - 2015-10-14 13:50 +0200
      Re: [PATCH 2/5] mtd: nand: omap2: Start dma request before enabling  prefetch "Franklin S Cooper Jr." <fcooper@ti.com> - 2015-10-14 15:50 +0200
  [PATCH 1/5] mtd: nand: omap2: Support parsing dma channel information from DT Franklin S Cooper Jr <fcooper@ti.com> - 2015-10-13 03:50 +0200
    Re: [PATCH 1/5] mtd: nand: omap2: Support parsing dma channel  information from DT Roger Quadros <rogerq@ti.com> - 2015-10-14 13:40 +0200
      Re: [PATCH 1/5] mtd: nand: omap2: Support parsing dma channel  information from DT Roger Quadros <rogerq@ti.com> - 2015-10-14 14:00 +0200
        Re: [PATCH 1/5] mtd: nand: omap2: Support parsing dma channel  information from DT "Franklin S Cooper Jr." <fcooper@ti.com> - 2015-10-14 15:30 +0200
          Re: [PATCH 1/5] mtd: nand: omap2: Support parsing dma channel  information from DT Roger Quadros <rogerq@ti.com> - 2015-10-14 16:20 +0200
            Re: [PATCH 1/5] mtd: nand: omap2: Support parsing dma channel  information from DT "Franklin S Cooper Jr." <fcooper@ti.com> - 2015-10-14 16:40 +0200
              Re: [PATCH 1/5] mtd: nand: omap2: Support parsing dma channel  information from DT Tony Lindgren <tony@atomide.com> - 2015-10-14 18:20 +0200
                Re: [PATCH 1/5] mtd: nand: omap2: Support parsing dma channel  information from DT "Franklin S Cooper Jr." <fcooper@ti.com> - 2015-10-14 18:30 +0200
                Re: [PATCH 1/5] mtd: nand: omap2: Support parsing dma channel  information from DT Tony Lindgren <tony@atomide.com> - 2015-10-14 20:20 +0200
                Re: [PATCH 1/5] mtd: nand: omap2: Support parsing dma channel  information from DT "Franklin S Cooper Jr." <fcooper@ti.com> - 2015-10-14 22:10 +0200
                Re: [PATCH 1/5] mtd: nand: omap2: Support parsing dma channel  information from DT Roger Quadros <rogerq@ti.com> - 2015-10-15 09:40 +0200
                Re: [PATCH 1/5] mtd: nand: omap2: Support parsing dma channel  information from DT "Franklin S Cooper Jr." <fcooper@ti.com> - 2015-10-15 19:20 +0200

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