From: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
To: Tali Perry <tali.perry1@gmail.com>
Cc: "Tomer Maimon" <tmaimon77@gmail.com>,
devicetree <devicetree@vger.kernel.org>,
yangyicong@hisilicon.com, "Linux I2C" <linux-i2c@vger.kernel.org>,
"Benjamin Fair" <benjaminfair@google.com>,
"OpenBMC Maillist" <openbmc@lists.ozlabs.org>,
JJLIU0@nuvoton.com, lukas.bulwahn@gmail.com,
tomer.maimon@nuvoton.com, KWLIU@nuvoton.com, bence98@sch.bme.hu,
arnd@arndb.de, sven@svenpeter.dev,
"Jonathan Neuschäfer" <j.neuschaefer@gmx.net>,
"Rob Herring" <robh+dt@kernel.org>,
"Avi Fishman" <Avi.Fishman@nuvoton.com>,
"Tyrone Ting" <warp5tw@gmail.com>,
"Andy Shevchenko" <andriy.shevchenko@linux.intel.com>,
semen.protsenko@linaro.org, jie.deng@intel.com,
avifishman70@gmail.com, "Patrick Venture" <venture@google.com>,
"Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>,
"Wolfram Sang" <wsa@kernel.org>,
kfting@nuvoton.com, "Tali Perry" <tali.perry@nuvoton.com>,
olof@lixom.net
Subject: Re: [PATCH v1 6/6] i2c: npcm: Support NPCM845
Date: Tue, 8 Feb 2022 08:59:05 +0100 [thread overview]
Message-ID: <30ac5fe7-9d96-a756-24b0-384361b48a2d@canonical.com> (raw)
In-Reply-To: <CAHb3i=vpFwez+ZzDhHkSxjkios3tyoM2urRpCxOn3vfwzvewog@mail.gmail.com>
On 08/02/2022 08:14, Tali Perry wrote:
>> -----Original Message-----
>> From: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
>> Sent: Monday, February 7, 2022 5:27 PM
>> To: Jonathan Neuschäfer <j.neuschaefer@gmx.net>; Tyrone Ting <warp5tw@gmail.com>
>> Cc: avifishman70@gmail.com; tmaimon77@gmail.com; tali.perry1@gmail.com; venture@google.com; yuenn@google.com; benjaminfair@google.com; robh+dt@kernel.org; semen.protsenko@linaro.org; yangyicong@hisilicon.com; wsa@kernel.org; jie.deng@intel.com; sven@svenpeter.dev; bence98@sch.bme.hu; lukas.bulwahn@gmail.com; arnd@arndb.de; olof@lixom.net; andriy.shevchenko@linux.intel.com; IS20 Tali Perry <tali.perry@nuvoton.com>; IS20 Avi Fishman <Avi.Fishman@nuvoton.com>; IS20 Tomer Maimon <tomer.maimon@nuvoton.com>; CS20 KWLiu <KWLIU@nuvoton.com>; CS20 JJLiu0 <JJLIU0@nuvoton.com>; CS20 KFTing <KFTING@nuvoton.com>; devicetree@vger.kernel.org; openbmc@lists.ozlabs.org; linux-i2c@vger.kernel.org; linux-kernel@vger.kernel.org
>> Subject: Re: [PATCH v1 6/6] i2c: npcm: Support NPCM845
>>
>> On 07/02/2022 13:00, Jonathan Neuschäfer wrote:
>>> Hello,
>>>
>>> On Mon, Feb 07, 2022 at 02:33:38PM +0800, Tyrone Ting wrote:
>>>> From: Tyrone Ting <kfting@nuvoton.com>
>>>>
>>>> NPCM8XX uses a similar i2c module as NPCM7XX.
>>>> The only difference is that the internal HW FIFO is larger.
>>>>
>>>> Related Makefile and Kconfig files are modified to support as well.
>>>>
>>>> Fixes: 56a1485b102e ("i2c: npcm7xx: Add Nuvoton NPCM I2C controller
>>>> driver")
>>>
>>> It's not really a bug fix, but rather an additional feature.
>>> Therefore, I suggest removing the Fixes tag from this patch.
>>>
>>>> Signed-off-by: Tyrone Ting <kfting@nuvoton.com>
>>>> Signed-off-by: Tali Perry <tali.perry1@gmail.com>
>>>> ---
>>> [...]
>>>> /* init register and default value required to enable module */
>>>> #define NPCM_I2CSEGCTL 0xE4
>>>> +#ifdef CONFIG_ARCH_NPCM7XX
>>>> #define NPCM_I2CSEGCTL_INIT_VAL 0x0333F000
>>>> +#else
>>>> +#define NPCM_I2CSEGCTL_INIT_VAL 0x9333F000
>>>> +#endif
>>>
>>> This is going to cause problems when someone tries to compile a kernel
>>> that runs on both NPCM7xx and NPCM8xx (because the driver will then
>>> only work on NPCM7xx).
>>
>> Yes, good catch.
>>
>> The NPCM7XX is multiplatform, I guess NPCM8xx will be as well, so this looks like an invalid code. How such code is supposed to work on multiplatform kernel?
>>
>
> NPCM7xx and NPCM8xx are very different devices.
> They share same driver sources for some of the modules but it's not ABI.
> Users cannot compile a single kernel with two separate DTS.
> In case of the i2c controller, the npcm7xx has a 16 byte HW FIFO,
> and the NPCM8xx has 32 bytes HW FIFO.
> This also means that registers fields are slightly different.
> For init data we can move it to the DTS, but register field sizes
> can't be handled with this approach.
>
What do you mean they cannot compile a kernel with different DTS? Of
course they can - when we talk about multiplatform sub-architectures!
Maybe there is something specific in NPCMxxx which stops it but then it
should not be marked multiplatform.
Best regards,
Krzysztof
next prev parent reply other threads:[~2022-02-08 8:00 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-07 6:33 [PATCH v1 0/6] i2c: npcm: Bug fixes timeout, spurious interrupts Tyrone Ting
2022-02-07 6:33 ` [PATCH v1 1/6] dt-bindings: i2c: npcm: support NPCM845 Tyrone Ting
2022-02-07 11:21 ` Jonathan Neuschäfer
2022-02-07 11:27 ` Krzysztof Kozlowski
2022-02-07 14:22 ` Rob Herring
2022-02-08 8:44 ` warp5tw
2022-02-08 9:03 ` warp5tw
2022-02-11 16:14 ` Rob Herring
2022-02-12 3:19 ` warp5tw
2022-02-07 6:33 ` [PATCH v1 2/6] i2c: npcm: Fix timeout calculation Tyrone Ting
2022-02-07 11:21 ` Krzysztof Kozlowski
2022-02-07 11:27 ` Jonathan Neuschäfer
2022-02-08 9:09 ` warp5tw
2022-02-07 6:33 ` [PATCH v1 3/6] i2c: npcm: Add tx complete counter Tyrone Ting
2022-02-07 6:33 ` [PATCH v1 4/6] i2c: npcm: Handle spurious interrupts Tyrone Ting
2022-02-07 11:40 ` Jonathan Neuschäfer
2022-02-08 9:19 ` warp5tw
2022-02-07 6:33 ` [PATCH v1 5/6] i2c: npcm: Remove own slave addresses 2:10 Tyrone Ting
2022-02-07 6:33 ` [PATCH v1 6/6] i2c: npcm: Support NPCM845 Tyrone Ting
2022-02-07 12:00 ` Jonathan Neuschäfer
2022-02-07 15:26 ` Krzysztof Kozlowski
2022-02-08 7:11 ` tali.perry
2022-02-08 7:14 ` Tali Perry
2022-02-08 7:59 ` Krzysztof Kozlowski [this message]
2022-02-08 8:51 ` Tali Perry
2022-02-08 8:56 ` Krzysztof Kozlowski
2022-02-08 9:22 ` Tali Perry
2022-02-08 9:29 ` Krzysztof Kozlowski
2022-02-08 9:31 ` Avi Fishman
2022-02-08 9:39 ` Krzysztof Kozlowski
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