linux-kernel - Re: [PATCH 2/5] mtd: nand: gpmi: add i.MX 7 SoC support

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Date:   Fri, 21 Apr 2017 10:38:28 -0700
From:   Stefan Agner <stefan@...er.ch>
To:     Marek Vasut <marek.vasut@...il.com>
Cc:     dwmw2@...radead.org, computersforpeace@...il.com,
        boris.brezillon@...e-electrons.com, richard@....at,
        cyrille.pitchen@...el.com, robh+dt@...nel.org,
        mark.rutland@....com, shawnguo@...nel.org, kernel@...gutronix.de,
        han.xu@....com, fabio.estevam@...escale.com,
        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 2/5] mtd: nand: gpmi: add i.MX 7 SoC support

On 2017-04-21 10:22, Marek Vasut wrote:
> On 04/21/2017 06:19 PM, Stefan Agner wrote:
>> On 2017-04-21 06:08, Marek Vasut wrote:
>>> On 04/21/2017 05:15 AM, Stefan Agner wrote:
>>>> On 2017-04-20 19:03, Marek Vasut wrote:
>>>>> On 04/21/2017 03:07 AM, Stefan Agner wrote:
>>>>>> Add support for i.MX 7 SoC. The i.MX 7 has a slightly different
>>>>>> clock architecture requiring only two clocks to be referenced.
>>>>>> The IP is slightly different compared to i.MX 6SoloX, but currently
>>>>>> none of this differences are in use so there is no detection needed
>>>>>> and the driver can reuse IS_MX6SX.
>>>>>>
>>>>>> Signed-off-by: Stefan Agner <stefan@...er.ch>
>>>>>> ---
>>>>>>  drivers/mtd/nand/gpmi-nand/gpmi-nand.c | 15 +++++++++++++++
>>>>>>  1 file changed, 15 insertions(+)
>>>>>>
>>>>>> diff --git a/drivers/mtd/nand/gpmi-nand/gpmi-nand.c b/drivers/mtd/nand/gpmi-nand/gpmi-nand.c
>>>>>> index c8bbf5da2ab8..4a45d37ddc80 100644
>>>>>> --- a/drivers/mtd/nand/gpmi-nand/gpmi-nand.c
>>>>>> +++ b/drivers/mtd/nand/gpmi-nand/gpmi-nand.c
>>>>>> @@ -127,6 +127,18 @@ static const struct gpmi_devdata gpmi_devdata_imx6sx = {
>>>>>>  	.clks_count = ARRAY_SIZE(gpmi_clks_for_mx6),
>>>>>>  };
>>>>>>
>>>>>> +static const char * const gpmi_clks_for_mx7d[] = {
>>>>>> +	"gpmi_io", "gpmi_bch_apb",
>>>>>> +};
>>>>>> +
>>>>>> +static const struct gpmi_devdata gpmi_devdata_imx7d = {
>>>>>> +	.type = IS_MX6SX,
>>>>>
>>>>> Would it make sense to use IS_MX7 here already to prevent future surprises ?
>>>>>
>>>>
>>>> Yeah I was thinking we can do it once we have an actual reason to
>>>> distinguish.
>>>
>>> So what are the differences anyway ?
>>>
>>
>> I did not check the details, but Han's patchset (link in cover letter)
>> mentions:
>> "add the HW bitflip detection and correction for i.MX6QP and i.MX7D."...
> 
> Oh, interesting.
> 
>>>> But then, adding the type would only require 2-3 lines of change if I
>>>> add it to the GPMI_IS_MX6 macro...
>>>
>>> Then at least add a comment because using type = IMX6SX right under
>>> gpmi_data_mx7d can trigger some head-scratching. And put my R-B on V2.
>>
>> FWIW, I mentioned it in the commit message.
>>
>> I think rather then adding a comment it is cleaner to just add IS_IMX7D
>> and add it to the GPMI_IS_MX6 macro. That does not need a comment since
>> it implicitly says we have a i.MX 7 but treat it like i.MX 6 and it is a
>> rather small change. Does that sound acceptable?
> 
> Sure, that's even better, thanks.
> 
> btw isn't there some single-core mx7 (mx7s ?) , maybe we should just go
> with mx7 (without the d suffix). I dunno if it has GPMI NAND though, so
> maybe mx7d is the right thing to do here ...
> 

There is a Solo version yes, and it has GPMI NAND too. However, almost
all i.MX 7 IPs have been named imx7d by NXP for some reason (including
compatible strings, see grep -r -e imx7 Documentation/), so I thought I
stay consistent here...

--
Stefan

>> --- a/drivers/mtd/nand/gpmi-nand/gpmi-nand.c
>> +++ b/drivers/mtd/nand/gpmi-nand/gpmi-nand.c
>> @@ -132,7 +132,7 @@ static const char * const gpmi_clks_for_mx7d[] = {
>>  };
>>
>>  static const struct gpmi_devdata gpmi_devdata_imx7d = {
>> -       .type = IS_MX6SX,
>> +       .type = IS_MX7D,
>>         .bch_max_ecc_strength = 62,
>>         .max_chain_delay = 12,
>>         .clks = gpmi_clks_for_mx7d,
>> diff --git a/drivers/mtd/nand/gpmi-nand/gpmi-nand.h
>> b/drivers/mtd/nand/gpmi-nand/gpmi-nand.h
>> index 2e584e18d980..f2cc13abc896 100644
>> --- a/drivers/mtd/nand/gpmi-nand/gpmi-nand.h
>> +++ b/drivers/mtd/nand/gpmi-nand/gpmi-nand.h
>> @@ -123,7 +123,8 @@ enum gpmi_type {
>>         IS_MX23,
>>         IS_MX28,
>>         IS_MX6Q,
>> -       IS_MX6SX
>> +       IS_MX6SX,
>> +       IS_MX7D,
>>  };
>>
>>  struct gpmi_devdata {
>> @@ -307,6 +308,8 @@ void gpmi_copy_bits(u8 *dst, size_t dst_bit_off,
>>  #define GPMI_IS_MX28(x)                ((x)->devdata->type == IS_MX28)
>>  #define GPMI_IS_MX6Q(x)                ((x)->devdata->type == IS_MX6Q)
>>  #define GPMI_IS_MX6SX(x)       ((x)->devdata->type == IS_MX6SX)
>> +#define GPMI_IS_MX7D(x)                ((x)->devdata->type == IS_MX7D)
>>
>> -#define GPMI_IS_MX6(x)         (GPMI_IS_MX6Q(x) || GPMI_IS_MX6SX(x))
>> +#define GPMI_IS_MX6(x)         (GPMI_IS_MX6Q(x) || GPMI_IS_MX6SX(x) ||
>> \
>> +                                GPMI_IS_MX7D(x))
>>  #endif
>>
>> --
>> Stefan
>>