linux-kernel - Re: [PATCH v1] i3c/master: cmd_v1: Fix the rule for getting i3c mode

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Message-ID: <cc94e66f-6fa0-4499-a851-bac90533eeca@quicinc.com>
Date: Thu, 5 Sep 2024 11:20:29 +0530
From: Mukesh Kumar Savaliya <quic_msavaliy@...cinc.com>
To: Billy Tsai <billy_tsai@...eedtech.com>,
        "alexandre.belloni@...tlin.com"
	<alexandre.belloni@...tlin.com>,
        "jarkko.nikula@...ux.intel.com"
	<jarkko.nikula@...ux.intel.com>,
        "linux-i3c@...ts.infradead.org"
	<linux-i3c@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v1] i3c/master: cmd_v1: Fix the rule for getting i3c mode


Hi Billy,

On 8/26/2024 9:32 AM, Billy Tsai wrote:
>> Based on the I3C TCRI specification, the rules for determining the I3C
>> mode are as follows:
>> I3C SCL rate > 8MHz: use SDR0, with a maximum data rate of 8MHz
>> I3C SCL rate > 6MHz: use SDR1, with a maximum data rate of 6MHz
>> I3C SCL rate > 4MHz: use SDR2, with a maximum data rate of 4MHz
>> I3C SCL rate > 2MHz: use SDR3, with a maximum data rate of 2MHz
>> Otherwise, use SDR4
> 
> Sorry, the description of the commit message is wrong.
> I will change it to
> I3C SCL rate > 8MHz: use SDR0, as SDR1 has a maximum data rate of 8MHz
> I3C SCL rate > 6MHz: use SDR1, as SDR2 has a maximum data rate of 8MHz
> I3C SCL rate > 4MHz: use SDR2, as SDR3 has a maximum data rate of 8MHz
> I3C SCL rate > 2MHz: use SDR3, as SDR4 has a maximum data rate of 8MHz
> I3C SCL rate <= 2MHz: use SDR4
> and send the v2 patch
Seems some typo errors, you mentioned all the modes having maximum data 
rate of 8MHz. "has a maximum data rate of 8MHz"

I3C TCRI Specification (in [MIPI06] Section 7.1.1.1) :
MODE 	Listed Speed 	Maximum Sustainable Data Rate
0x0 	I3C SDR0 	12.5 MHz, Standard SDR Speed, fSCL Max
0x1 	I3C SDR1 	8 MHz
0x2 	I3C SDR2 	6 MHz
0x3 	I3C SDR3 	4 MHz
0x4 	I3C SDR4 	2 MHz