linux-kernel - [PATCH] i2c: riic: Allow setting frequencies lower than 50KHz

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Message-ID: <20250923141826.3765925-1-claudiu.beznea.uj@bp.renesas.com>
Date: Tue, 23 Sep 2025 17:18:26 +0300
From: Claudiu <claudiu.beznea@...on.dev>
To: chris.brandt@...esas.com,
	andi.shyti@...nel.org,
	wsa@...nel.org
Cc: claudiu.beznea@...on.dev,
	linux-renesas-soc@...r.kernel.org,
	linux-i2c@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
Subject: [PATCH] i2c: riic: Allow setting frequencies lower than 50KHz

From: Claudiu Beznea <claudiu.beznea.uj@...renesas.com>

The MR1.CKS field is 3 bits wide and all the possible values (from 0 to
7) are valid. This is true for all the SoCs currently integrated in
upstream Linux. Take into account CKS=7 which allows setting bus
frequencies lower than 50KHz. This may be useful at least for debugging.

Fixes: d982d6651419 ("i2c: riic: remove clock and frequency restrictions")
Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
---
 drivers/i2c/busses/i2c-riic.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/i2c/busses/i2c-riic.c b/drivers/i2c/busses/i2c-riic.c
index 9c164a4b9bb9..b0ee9ac45a97 100644
--- a/drivers/i2c/busses/i2c-riic.c
+++ b/drivers/i2c/busses/i2c-riic.c
@@ -386,7 +386,7 @@ static int riic_init_hw(struct riic_dev *riic)
 	 */
 	total_ticks = DIV_ROUND_UP(rate, t->bus_freq_hz ?: 1);
 
-	for (cks = 0; cks < 7; cks++) {
+	for (cks = 0; cks <= 7; cks++) {
 		/*
 		 * 60% low time must be less than BRL + 2 + 1
 		 * BRL max register value is 0x1F.
-- 
2.43.0