linux-kernel - Re: [PATCH] spmi-pmic-arb: support configurable number of peripherals

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Message-Id: <8EEAE898-347B-4CEA-BA4D-0C69897E18EB@gmail.com>
Date:	Thu, 15 Oct 2015 12:23:18 +0300
From:	"Ivan T. Ivanov" <iivanov.xz@...il.com>
To:	Stephen Boyd <sboyd@...eaurora.org>
Cc:	"Ivan T. Ivanov" <iivanov@...sol.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	Gilad Avidov <gavidov@...eaurora.org>,
	Sagar Dharia <sdharia@...eaurora.org>
Subject: Re: [PATCH] spmi-pmic-arb: support configurable number of peripherals


> On Oct 15, 2015, at 1:43 AM, Stephen Boyd <sboyd@...eaurora.org> wrote:
> 
> On 09/15/2015 11:27 AM, Stephen Boyd wrote:
>> On 09/15, Ivan T. Ivanov wrote:
>>> On Mon, 2015-09-14 at 18:28 -0700, Stephen Boyd wrote:
>>>> On 09/14/2015 02:54 PM, Stephen Boyd wrote:
>>>>> The current driver implementation supports only 128 peripherals.
>>>>> Add support for more than 128 peripherals by taking a lazy
>>>>> caching approach to the mapping tables. Instead of reading the
>>>>> tables at boot given some fixed size, read them on an as needed
>>>>> basis and cache the results. We still assume a max number of 512
>>>>> peripherals, trading off some space for simplicity.
>>>>> 
>>>>> Based on a patch by Gilad Avidov <gavidov@...eaurora.org> and
>>>>> Sagar Dharia <sdharia@...eaurora.org>.
>>>>> 
>>>>> Signed-off-by: Stephen Boyd <sboyd@...eaurora.org>
>>>>> ---
>>>> Hi Ivan,
>>>> 
>>>> This patch causes 8916 to crash, because there isn't a mapping for ppid
>>>> 257 in the ppid to channel table. It seems that we're reading the revid
>>>> from the slave id 1 pmic by going through channel 0, which seems to be
>>>> setup for ppid 9 (slave id 0 and the peripheral starting at 0x900). Can
>>>> we stop reading the revid registers from non-zero slave id pmic devices?
>>>> That would be one solution to fix this problem. Or maybe we need to
>>>> special case this in the pmic arbiter code to fold ppid 0xN01 (slave id
>>>> N and address 0x100) onto channel 0 all the time?
>>>> 
>>> Yes, we can. We are not using this information at the moment.
>>> Right now, revision read is more or less for debug purposes.
>>> 
>>> Would following patch work for you? Of course it will be difficult
>> Yes the patch works fine. Feel free to add a
>> 
>> Tested-by: Stephen Boyd <sboyd@...eaurora.org>
>> 
>> 
> 
> I have to take this back. I missed the part where some pmics are on
> slave id 2 or slave id 4, so this check isn't going to work. I've
> adjusted it to use sid % 2 instead and I'll resend these two patches,
> but I imagine to be more robust we're going to need to add a revid node
> to the DT under the SID that actually has it. Then we can search the
> child nodes for a revid compatible node and do the rev probing stuff.

Ah, yes. We don’t use revision information for now. 
I suppose we can just remove these reads until we need
this information?

Regards,
Ivan

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