Re: [PATCH v2 06/17] i3c: renesas: Perform Dynamic Address Assignment on resume

From: Frank Li <Frank.li@nxp.com>
To: Claudiu Beznea <claudiu.beznea@kernel.org>
Cc: wsa+renesas@sang-engineering.com,
	tommaso.merciai.xr@bp.renesas.com, alexandre.belloni@bootlin.com,
	p.zabel@pengutronix.de, claudiu.beznea@tuxon.dev,
	linux-i3c@lists.infradead.org, linux-kernel@vger.kernel.org,
	Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>,
	stable@vger.kernel.org
Subject: Re: [PATCH v2 06/17] i3c: renesas: Perform Dynamic Address Assignment on resume
Date: Tue, 2 Jun 2026 16:12:53 -0400	[thread overview]
Message-ID: <ah85RaUXmaBVFkYk@lizhi-Precision-Tower-5810> (raw)
In-Reply-To: <20260602132824.3541151-7-claudiu.beznea@kernel.org>

On Tue, Jun 02, 2026 at 04:28:13PM +0300, Claudiu Beznea wrote:
> From: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
>
> The Renesas RZ/G3S SoC supports a power saving mode where power to most
> SoC components, including I3C, is turned off.
>
> On systems where the I3C devices also loses power during suspend (e.g. NXP
> P3T1085UK-ARD connected to the PMOD1_6A connector of the RZ SMARC Carrier
> 2 + Renesas RZ/G3S SMARC SOM), the devices becomes unreachable after
> resume.
>
> Running DAA in the controller resume path restores communication. However,
> DAA relies on interrupts for TX/RX, which are not available in the noirq
> suspend/resume phase (unless they are wakeup interrupts). For this, the
> suspend/resume callbacks were moved out of the noirq phase. Currently,
> there is no identified use case on either the Renesas RZ/G3S or Renesas
> RZ/G3E SoCs that requires the controller suspend/resume hooks to be part of
> the noirq suspend/resume phase.
>
> Since renesas_i3c_reset() is not called anymore in atomic context
> update it to use read_poll_timeout().
>
> To cover the case where the controller had already attached all the
> i3c->maxdevs devices before a suspend/resume cycle and i3c->free_pos is
> zero, struct renesas_i3c::resuming flag was introduced.
>
> The flag is set in renesas_i3c_resume() before calling
> i3c_master_do_daa_ext() and checked in renesas_i3c_daa(). In case it is
> set the previous saved DATBAS register values are used for the slots
> already occupied before suspend. This allows keeping alive the connection
> to the I3C devices when all the supported slots are occupied before
> suspend.
>
> When resuming from suspend, renesas_i3c_daa() re-runs DAA for al
> slots except those used by I2C devices. I2C devices are attached during
> probe, at bus initialization time, and always occupy the first positions in
> i3c->free_pos. In addition, there are no DATBAS register settings
> associated with them.
>
> Fixes: e7218986319b ("i3c: renesas: Add suspend/resume support")
> Cc: stable@vger.kernel.org
> Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
> ---

Please check sashiko review result

https://sashiko.dev/#/patchset/20260602132824.3541151-1-claudiu.beznea%40kernel.org

Frank

>

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