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From: Kewei Xu <kewei.xu@mediatek.com>
To: <wsa@the-dreams.de>
Cc: <matthias.bgg@gmail.com>, <robh+dt@kernel.org>,
	<linux-i2c@vger.kernel.org>, <devicetree@vger.kernel.org>,
	<linux-arm-kernel@lists.infradead.org>,
	<linux-kernel@vger.kernel.org>,
	<linux-mediatek@lists.infradead.org>,
	<srv_heupstream@mediatek.com>, <leilk.liu@mediatek.com>,
	<qii.wang@mediatek.com>, <liguo.zhang@mediatek.com>,
	<caiyu.chen@mediatek.com>, <ot_daolong.zhu@mediatek.com>,
	<yuhan.wei@mediatek.com>, <kewei.xu@mediatek.com>
Subject: [RESEND PATCH v5 7/7] i2c: mediatek: modify bus speed calculation formula
Date: Tue, 24 Aug 2021 11:30:28 +0800	[thread overview]
Message-ID: <1629775828-19993-8-git-send-email-kewei.xu@mediatek.com> (raw)
In-Reply-To: <1629775828-19993-1-git-send-email-kewei.xu@mediatek.com>

When clock-div is 0 or greater than 1, the bus speed
calculated by the old speed calculation formula will be
larger than the target speed. So we update the formula.

Signed-off-by: Kewei Xu <kewei.xu@mediatek.com>
---
 drivers/i2c/busses/i2c-mt65xx.c | 35 +++++++++++++++++++++++++----------
 1 file changed, 25 insertions(+), 10 deletions(-)

diff --git a/drivers/i2c/busses/i2c-mt65xx.c b/drivers/i2c/busses/i2c-mt65xx.c
index 18b5659..0b42acd8 100644
--- a/drivers/i2c/busses/i2c-mt65xx.c
+++ b/drivers/i2c/busses/i2c-mt65xx.c
@@ -69,11 +69,12 @@
 #define I2C_DEFAULT_CLK_DIV		5
 #define MAX_SAMPLE_CNT_DIV		8
 #define MAX_STEP_CNT_DIV		64
-#define MAX_CLOCK_DIV			256
+#define MAX_CLOCK_DIV_8BITS		256
+#define MAX_CLOCK_DIV_5BITS		32
 #define MAX_HS_STEP_CNT_DIV		8
-#define I2C_STANDARD_MODE_BUFFER	(1000 / 2)
-#define I2C_FAST_MODE_BUFFER		(300 / 2)
-#define I2C_FAST_MODE_PLUS_BUFFER	(20 / 2)
+#define I2C_STANDARD_MODE_BUFFER	(1000 / 3)
+#define I2C_FAST_MODE_BUFFER		(300 / 3)
+#define I2C_FAST_MODE_PLUS_BUFFER	(20 / 3)
 
 #define I2C_CONTROL_RS                  (0x1 << 1)
 #define I2C_CONTROL_DMA_EN              (0x1 << 2)
@@ -725,14 +726,26 @@ static int mtk_i2c_calculate_speed(struct mtk_i2c *i2c, unsigned int clk_src,
 	unsigned int best_mul;
 	unsigned int cnt_mul;
 	int ret = -EINVAL;
+	int clock_div_constraint = 0;
 
 	if (target_speed > I2C_MAX_HIGH_SPEED_MODE_FREQ)
 		target_speed = I2C_MAX_HIGH_SPEED_MODE_FREQ;
 
+	if (i2c->use_default_timing) {
+		clock_div_constraint = 0;
+	} else if (i2c->dev_comp->ltiming_adjust &&
+		   i2c->ac_timing.inter_clk_div > 1) {
+		clock_div_constraint = 1;
+	} else if (i2c->dev_comp->ltiming_adjust &&
+		   i2c->ac_timing.inter_clk_div == 0) {
+		clock_div_constraint = -1;
+	}
+
 	max_step_cnt = mtk_i2c_max_step_cnt(target_speed);
 	base_step_cnt = max_step_cnt;
 	/* Find the best combination */
-	opt_div = DIV_ROUND_UP(clk_src >> 1, target_speed);
+	opt_div = DIV_ROUND_UP(clk_src >> 1, target_speed) +
+		  clock_div_constraint;
 	best_mul = MAX_SAMPLE_CNT_DIV * max_step_cnt;
 
 	/* Search for the best pair (sample_cnt, step_cnt) with
@@ -767,7 +780,8 @@ static int mtk_i2c_calculate_speed(struct mtk_i2c *i2c, unsigned int clk_src,
 	sample_cnt = base_sample_cnt;
 	step_cnt = base_step_cnt;
 
-	if ((clk_src / (2 * sample_cnt * step_cnt)) > target_speed) {
+	if ((clk_src / (2 * (sample_cnt * step_cnt - clock_div_constraint))) >
+		 target_speed) {
 		/* In this case, hardware can't support such
 		 * low i2c_bus_freq
 		 */
@@ -854,13 +868,16 @@ static int mtk_i2c_set_speed_adjust_timing(struct mtk_i2c *i2c,
 	target_speed = i2c->speed_hz;
 	parent_clk /= i2c->clk_src_div;
 
-	if (i2c->dev_comp->timing_adjust)
-		max_clk_div = MAX_CLOCK_DIV;
+	if (i2c->dev_comp->timing_adjust && i2c->dev_comp->ltiming_adjust)
+		max_clk_div = MAX_CLOCK_DIV_5BITS;
+	else if (i2c->dev_comp->timing_adjust)
+		max_clk_div = MAX_CLOCK_DIV_8BITS;
 	else
 		max_clk_div = 1;
 
 	for (clk_div = 1; clk_div <= max_clk_div; clk_div++) {
 		clk_src = parent_clk / clk_div;
+		i2c->ac_timing.inter_clk_div = clk_div - 1;
 
 		if (target_speed > I2C_MAX_FAST_MODE_PLUS_FREQ) {
 			/* Set master code speed register */
@@ -907,8 +924,6 @@ static int mtk_i2c_set_speed_adjust_timing(struct mtk_i2c *i2c,
 		break;
 	}
 
-	i2c->ac_timing.inter_clk_div = clk_div - 1;
-
 	return 0;
 }
 
-- 
1.9.1


      parent reply	other threads:[~2021-08-24  3:31 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-24  3:30 [RESEND PATCH v5 0/7] Introducing an attribute to select the time setting Kewei Xu
2021-08-24  3:30 ` [RESEND PATCH v5 1/7] i2c: mediatek: fixing the incorrect register offset Kewei Xu
2021-08-24  3:30 ` [RESEND PATCH v5 2/7] i2c: mediatek: Reset the handshake signal between i2c and dma Kewei Xu
2021-08-24  3:30 ` [RESEND PATCH v5 3/7] i2c: mediatek: Dump i2c/dma register when a timeout occurs Kewei Xu
2021-08-24  3:30 ` [RESEND PATCH v5 4/7] dt-bindings: i2c: add attribute use-default-timing Kewei Xu
2021-08-24 16:52   ` Rob Herring
2021-08-24  3:30 ` [RESEND PATCH v5 5/7] i2c: mediatek: Add OFFSET_EXT_CONF setting back Kewei Xu
2021-08-24  3:30 ` [RESEND PATCH v5 6/7] i2c: mediatek: Isolate speed setting via dts for special devices Kewei Xu
2021-08-24  3:30 ` Kewei Xu [this message]

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