* Tony Lindgren <tony@xxxxxxxxxxx> [080331 13:43]: > * Tony Lindgren <tony@xxxxxxxxxxx> [080328 10:41]: > > Hi all, > > > > This helps with the annoying I2C timeouts. Does anybody have an idea > > why the twl4030 chip does not like doing multiple transfers in a row? > > > > To me the only difference seems to be that clocks are idled between > > writing the twl4030 register and reading the register value. > > I'll push this today with a REVISIT comment added. Looks like this kills twl4030 interrupts, so I've reverted it. Tony > > From 25c4c8f449819cb6f40b59ed1a9b25ebcc7cd72e Mon Sep 17 00:00:00 2001 > > From: Tony Lindgren <tony@xxxxxxxxxxx> > > Date: Thu, 27 Mar 2008 19:05:30 +0200 > > Subject: [PATCH] I2C: Fix twl4030 timeouts on omap3430 > > > > For some reason doing a twl4030 write-read cycle can hang the I2C bus > > on omap3430. And doing the write and read separately in twl4030_i2c_read() > > seems to fix the problem... > > > > Not intended for applying, just a temporary workaround. > > > > diff --git a/drivers/i2c/chips/twl4030-core.c b/drivers/i2c/chips/twl4030-core.c > > index ded86e7..62868b0 100644 > > --- a/drivers/i2c/chips/twl4030-core.c > > +++ b/drivers/i2c/chips/twl4030-core.c > > @@ -327,6 +327,7 @@ int twl4030_i2c_read(u8 mod_no, u8 * value, u8 reg, u8 num_bytes) > > return -EPERM; > > } > > mutex_lock(&twl->xfer_lock); > > + > > /* [MSG1] fill the register address data */ > > msg = &twl->xfer_msg[0]; > > msg->addr = twl->address; > > @@ -334,18 +335,25 @@ int twl4030_i2c_read(u8 mod_no, u8 * value, u8 reg, u8 num_bytes) > > msg->flags = 0; /* Read the register value */ > > val = twl4030_map[mod_no].base + reg; > > msg->buf = &val; > > + ret = i2c_transfer(twl->client.adapter, twl->xfer_msg, 1); > > + if (ret < 0) > > + goto out; > > + > > /* [MSG2] fill the data rx buffer */ > > msg = &twl->xfer_msg[1]; > > msg->addr = twl->address; > > msg->flags = I2C_M_RD; /* Read the register value */ > > msg->len = num_bytes; /* only n bytes */ > > msg->buf = value; > > - ret = i2c_transfer(twl->client.adapter, twl->xfer_msg, 2); > > + ret = i2c_transfer(twl->client.adapter, twl->xfer_msg, 1); > > + > > +out: > > mutex_unlock(&twl->xfer_lock); > > > > /* i2cTransfer returns num messages.translate it pls.. */ > > if (ret >= 0) > > ret = 0; > > + > > return ret; > > } > > > -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
