Re: [PATCH v4] i2c: designware: Enable SAR in slave mode for Multiple SAR controllers

From: Andy Shevchenko

Date: Mon Aug 17 2026 - 07:10:59 EST


On Mon, Aug 17, 2026 at 02:10:23PM +0530, Umesh Kumar wrote:
> DesignWare controllers synthesised with the Multiple SAR feature (e.g.
> Marvell CN20K) gate the primary slave address behind IC_ENABLE.SAR_EN
> (bit 19). Per the Synopsys DW_apb_i2c DataBook v2.03a (Multiple SAR
> feature),when this bit is set the core acknowledges the address matching

Missing space after ).

> IC_SAR;otherwise the address is NACKed. The slave enable path writes only

Same here for ;.

> IC_ENABLE.ENABLE (bit 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.

Reviewed-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>

--
With Best Regards,
Andy Shevchenko