linux-kernel - Re: [PATCH v3 0/2] ARM: dts: imx7: add NAND support

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Date:   Thu, 01 Jun 2017 18:48:30 -0700
From:   Stefan Agner <stefan@...er.ch>
To:     Han Xu <han.xu@....com>
Cc:     shawnguo@...nel.org, kernel@...gutronix.de, dwmw2@...radead.org,
        computersforpeace@...il.com, boris.brezillon@...e-electrons.com,
        marek.vasut@...il.com, richard@....at, cyrille.pitchen@...el.com,
        robh+dt@...nel.org, mark.rutland@....com,
        fabio.estevam@...escale.com,
        "LW@...O-electronics.de" <LW@...o-electronics.de>,
        linux-mtd@...ts.infradead.org, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 0/2] ARM: dts: imx7: add NAND support

Hi Han,

On 2017-06-01 14:14, Han Xu wrote:
> On 06/01/2017 02:20 PM, Stefan Agner wrote:
>> This are the missing device tree parts to add NAND support for i.MX 7.
>> See previous patchset:
>> https://emea01.safelinks.protection.outlook.com/?url=https%3A%2F%2Flkml.org%2Flkml%2F2017%2F4%2F21%2F832&data=01%7C01%7Chan.xu%40nxp.com%7C3b9081a68c94476c4a2108d4a9235512%7C686ea1d3bc2b4c6fa92cd99c5c301635%7C0&sdata=mQ2aq5rW%2B9uADY5mSzFxk8P6bAVq%2BosPJQAi0PL9SQg%3D&reserved=0
>>
>> The previous version also included driver changes, which are already
>> merged.
>>
>> --
>> Stefan
>>
>> Changes since v2:
>> - Only specify IMX7D_NAND_USDHC_BUS_ROOT_CLK which seems to be sufficent
> Hi Stefan, sorry I didn't reply your last patch. I was unable to fully 
> test on i.MX7 since the work bandwidth, but the quick test shows DMA 
> cannot work WITHOUT IMX7D_NAND_ROOT_CLK on my side, I will fully check 
> it tomorrow morning and let you know the result.

How did you test that?

Since DMA can only use NAND in i.MX 7, testing is somewhat hard.

Fact is, I can access DMA registers using just NAND_USDHC_BUS_CLK_ROOT

mw.l 0x30388980 0x11000000 # Enable NAND_USDHC_BUS_CLK_ROOT
mw.l 0x3038aa00 0x00000000 # Enable NAND_CLK_ROOT

md.l 0x33000100 0 # Access APBH_CH0_CURCMDAR

This works for me.

I can *boot* from a UBIFS using this driver and Linux 4.12-rc1 with my
patchset applied...

Monitoring clocks in /sys/kernel/debug/clk/clk_summary show that
NAND_ROOT_CLK gets turned off and back on if NAND access happens, the
system seems stable.

All that said, this patchset v3 actually does not remove the
NAND_ROOT_CLK as intended to. Will send a v4.

--
Stefan

>> - Dropped driver changes, alreay merged
>>
>> Changes since v1:
>> - Make clks_count const
>> - Introduce IS_IMX7D for i.MX 7 SoC's and make it part of GPMI_IS_MX6
>>
>> Stefan Agner (2):
>>    ARM: dts: imx7: add GPMI NAND
>>    ARM: dts: imx7-colibri: add NAND support
>>
>>   arch/arm/boot/dts/imx7-colibri.dtsi |  9 +++++++++
>>   arch/arm/boot/dts/imx7s.dtsi        | 31 +++++++++++++++++++++++++++++++
>>   2 files changed, 40 insertions(+)
>>