Re: [PATCH v2] i2c: designware: Enable SAR in slave mode for Multiple SAR controllers

Andy Shevchenko <[email protected]> Wed, 12 Aug 2026 10:16:29 +0300

Newsgroups	org.kernel.vger.linux-i2c,org.kernel.vger.linux-kernel
Organization	Intel Finland Oy - BIC 0357606-4 - c/o Alberga Business Park, 6 krs, Bertel Jungin Aukio 5, 02600 Espoo
Message-ID	<[email protected]>

On Wed, Aug 12, 2026 at 09:10:17AM +0530, Umesh Kumar wrote:
> DesignWare controllers synthesised with the Multiple SAR feature (e.g.
> Marvell CN20K) only acknowledge traffic to the primary slave address
> (IC_SAR) when IC_ENABLE[19] (SAR_EN) is set. The slave enable path
> writes only IC_ENABLE[0], so on such controllers the target never ACKs
> its address and a remote master cannot reach it.
> 
> Set SAR_EN together with ENABLE when entering slave mode. The bit is
> reserved (and ignored) on single-SAR controllers, so existing users are
> unaffected.

In the commit message and in the code comment below, can we refer to Synopsys
DataBook for IÂ²C where this bit is described? Or is it Marvell custom bit?

-- 
With Best Regards,
Andy Shevchenko