Hi,
On 2015-02-15 15:43, Yoshihiro Kaneko wrote:
From: Ryo Kataoka <ryo.kataoka.wt@xxxxxxxxxxx>
In case of repeated START condition, the restart has to be kicked
before clear status (MSR register). If it is kicked after clear
status,
R-Car I2C may transfer data (TXD register) or receive data (RXD
register)
instead of transferring slave address (MAR register).
Signed-off-by: Ryo Kataoka <ryo.kataoka.wt@xxxxxxxxxxx>
Signed-off-by: Yoshihiro Kaneko <ykaneko0929@xxxxxxxxx>
Thanks for the patch!
I wondered if we couldn't always kick the start/restart before clearing
the status register?
I am not sure if this simulates the flaw accurately, but I inserted a
udelay(500)
in the original code after clearing the status register. Then, I
couldn't access
the audio codec on my Lager board anymore. By always first "kicking"
and then
clearing, access was possible again. But as said, I am not sure if my
scenario
matches yours. Have you considered to treat start and repeated start
the same
and always kick the condition before clearing the status?
Kind regards,
Wolfram
---
This patch is based on i2c/for-next branch of Wolfram Sang's linux
tree.
drivers/i2c/busses/i2c-rcar.c | 15 +++++++++++++--
1 file changed, 13 insertions(+), 2 deletions(-)
diff --git a/drivers/i2c/busses/i2c-rcar.c
b/drivers/i2c/busses/i2c-rcar.c
index 71a6e07..96c349f 100644
--- a/drivers/i2c/busses/i2c-rcar.c
+++ b/drivers/i2c/busses/i2c-rcar.c
@@ -2,6 +2,7 @@
* Driver for the Renesas RCar I2C unit
*
* Copyright (C) 2014 Wolfram Sang <wsa@xxxxxxxxxxxxxxxxxxxx>
+ * Copyright (C) 2013-2014 Renesas Electronics Corporation
*
* Copyright (C) 2012-14 Renesas Solutions Corp.
* Kuninori Morimoto <kuninori.morimoto.gx@xxxxxxxxxxx>
@@ -99,6 +100,7 @@
#define ID_DONE (1 << 2)
#define ID_ARBLOST (1 << 3)
#define ID_NACK (1 << 4)
+#define ID_FIRST_MSG (1 << 5)
enum rcar_i2c_type {
I2C_RCAR_GEN1,
@@ -125,6 +127,7 @@ struct rcar_i2c_priv {
#define rcar_i2c_is_recv(p) ((p)->msg->flags & I2C_M_RD)
#define rcar_i2c_flags_set(p, f) ((p)->flags |= (f))
+#define rcar_i2c_flags_clr(p, f) ((p)->flags &= ~(f))
#define rcar_i2c_flags_has(p, f) ((p)->flags & (f))
#define LOOP_TIMEOUT 1024
@@ -257,8 +260,14 @@ static void rcar_i2c_prepare_msg(struct
rcar_i2c_priv *priv)
int read = !!rcar_i2c_is_recv(priv);
rcar_i2c_write(priv, ICMAR, (priv->msg->addr << 1) | read);
- rcar_i2c_write(priv, ICMSR, 0);
- rcar_i2c_write(priv, ICMCR, RCAR_BUS_PHASE_START);
+ if (rcar_i2c_flags_has(priv, ID_FIRST_MSG)) { /* start */
+ rcar_i2c_write(priv, ICMSR, 0);
+ rcar_i2c_write(priv, ICMCR, RCAR_BUS_PHASE_START);
+ rcar_i2c_flags_clr(priv, ID_FIRST_MSG);
+ } else { /* restart */
+ rcar_i2c_write(priv, ICMCR, RCAR_BUS_PHASE_START);
+ rcar_i2c_write(priv, ICMSR, 0);
+ }
rcar_i2c_write(priv, ICMIER, read ? RCAR_IRQ_RECV : RCAR_IRQ_SEND);
}
@@ -524,6 +533,8 @@ static int rcar_i2c_master_xfer(struct
i2c_adapter *adap,
priv->msg = &msgs[i];
priv->pos = 0;
priv->flags = 0;
+ if (i == 0)
+ rcar_i2c_flags_set(priv, ID_FIRST_MSG);
if (i == num - 1)
rcar_i2c_flags_set(priv, ID_LAST_MSG);
--
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