Hello,
This series contains a real fix for the I2C controller of the Armada
XP SoC and a patch closer to a improvement than a fix.
They are independent and are only in the same series because they are
kind of fixes.
They are based on 3.10-rc4, and they will be small conflicts if they
are applied on top of i2c/for-next branch and on top of the series I
have just sent to add I2C Transaction Generator support. You can have
a look on the branch i2c-mv64xxx-fixes-bridge to get an idea on how to
resolve it. This branch is located at
https://github.com/MISL-EBU-System-SW/mainline-public.git
Thanks,
Zbigniew Bodek (2):
i2c-mv64xxx: Fix timing issue on Armada XP (errata FE-8471889)
i2c-mv64xxx: Abort the mv64xxx_of_config if clock-frequency is not
provided
drivers/i2c/busses/i2c-mv64xxx.c | 21 ++++++++++++++++++++-
1 file changed, 20 insertions(+), 1 deletion(-)
--
1.8.1.2
From: Zbigniew Bodek <[email protected]>
All the Armada XP (mv78230, mv78260 and mv78460) have a silicon issue
in the I2C controller which violate the i2c repeated start
timing. The I2C standard requires a minimum of 4.7us for the repeated
start condition whereas the I2C controller of the Armada XP this time
is 2.9us.
So this patch adds a 5us delay for the start case only if the
mv64xxx_i2c_errata_delay flag is set.
[[email protected]: Merge the incoming commits into
this single one]
[[email protected]: Reword the commit log]
Signed-off-by: Gregory CLEMENT <[email protected]>
Signed-off-by: Zbigniew Bodek <[email protected]>
---
drivers/i2c/busses/i2c-mv64xxx.c | 17 +++++++++++++++++
1 file changed, 17 insertions(+)
diff --git a/drivers/i2c/busses/i2c-mv64xxx.c b/drivers/i2c/busses/i2c-mv64xxx.c
index 1a3abd6..60cac9f 100644
--- a/drivers/i2c/busses/i2c-mv64xxx.c
+++ b/drivers/i2c/busses/i2c-mv64xxx.c
@@ -23,6 +23,7 @@
#include <linux/of_i2c.h>
#include <linux/clk.h>
#include <linux/err.h>
+#include <linux/delay.h>
/* Register defines */
#define MV64XXX_I2C_REG_SLAVE_ADDR 0x00
@@ -59,6 +60,12 @@
#define MV64XXX_I2C_STATUS_MAST_RD_ADDR_2_NO_ACK 0xe8
#define MV64XXX_I2C_STATUS_NO_STATUS 0xf8
+/*
+ * 5us delay in order to avoid repeated start
+ * timing violation on Armada XP SoC.
+ */
+static int mv64xxx_i2c_errata_delay;
+
/* Driver states */
enum {
MV64XXX_I2C_STATE_INVALID,
@@ -252,6 +259,9 @@ mv64xxx_i2c_do_action(struct mv64xxx_i2c_data *drv_data)
writel(drv_data->cntl_bits,
drv_data->reg_base + MV64XXX_I2C_REG_CONTROL);
drv_data->block = 0;
+ if (mv64xxx_i2c_errata_delay)
+ udelay(5);
+
wake_up(&drv_data->waitq);
break;
@@ -300,6 +310,9 @@ mv64xxx_i2c_do_action(struct mv64xxx_i2c_data *drv_data)
writel(drv_data->cntl_bits | MV64XXX_I2C_REG_CONTROL_STOP,
drv_data->reg_base + MV64XXX_I2C_REG_CONTROL);
drv_data->block = 0;
+ if (mv64xxx_i2c_errata_delay)
+ udelay(5);
+
wake_up(&drv_data->waitq);
break;
@@ -592,6 +605,10 @@ mv64xxx_of_config(struct mv64xxx_i2c_data *drv_data,
* So hard code the value to 1 second.
*/
drv_data->adapter.timeout = HZ;
+
+ if (!mv64xxx_i2c_errata_delay &&
+ of_machine_is_compatible("marvell,armadaxp"))
+ mv64xxx_i2c_errata_delay = 1;
out:
return rc;
#endif
--
1.8.1.2
From: Zbigniew Bodek <[email protected]>
This commit adds checking whether clock-frequency property acquisition
has succeeded. Do not waste time to find baud factors if there is no
information about the desired bus frequency in dts.
[[email protected]: Reword the commit log]
Signed-off-by: Gregory CLEMENT <[email protected]>
Signed-off-by: Zbigniew Bodek <[email protected]>
---
drivers/i2c/busses/i2c-mv64xxx.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/drivers/i2c/busses/i2c-mv64xxx.c b/drivers/i2c/busses/i2c-mv64xxx.c
index 60cac9f..88c2dd0 100644
--- a/drivers/i2c/busses/i2c-mv64xxx.c
+++ b/drivers/i2c/busses/i2c-mv64xxx.c
@@ -593,7 +593,9 @@ mv64xxx_of_config(struct mv64xxx_i2c_data *drv_data,
goto out;
}
tclk = clk_get_rate(drv_data->clk);
- of_property_read_u32(np, "clock-frequency", &bus_freq);
+ if ((rc = of_property_read_u32(np, "clock-frequency", &bus_freq)) != 0)
+ goto out;
+
if (!mv64xxx_find_baud_factors(bus_freq, tclk,
&drv_data->freq_n, &drv_data->freq_m)) {
rc = -EINVAL;
--
1.8.1.2
Dear Gregory CLEMENT,
On Fri, 7 Jun 2013 17:48:59 +0200, Gregory CLEMENT wrote:
> +/*
> + * 5us delay in order to avoid repeated start
> + * timing violation on Armada XP SoC.
> + */
> +static int mv64xxx_i2c_errata_delay;
This should probably be a per-I2C controller variable, i.e in
mv64xxx_i2c_data.
> + if (!mv64xxx_i2c_errata_delay &&
> + of_machine_is_compatible("marvell,armadaxp"))
> + mv64xxx_i2c_errata_delay = 1;
I am wondering whether it should be done this way, or using a separate
DT property.
Best regards,
Thomas
--
Thomas Petazzoni, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com
On Fri, Jun 07, 2013 at 05:49:00PM +0200, Gregory CLEMENT wrote:
> From: Zbigniew Bodek <[email protected]>
>
> This commit adds checking whether clock-frequency property acquisition
> has succeeded. Do not waste time to find baud factors if there is no
> information about the desired bus frequency in dts.
>
> [[email protected]: Reword the commit log]
>
> Signed-off-by: Gregory CLEMENT <[email protected]>
> Signed-off-by: Zbigniew Bodek <[email protected]>
Please run checkpatch.pl on your patches!
On Fri, Jun 07, 2013 at 06:25:00PM +0200, Thomas Petazzoni wrote:
> Dear Gregory CLEMENT,
>
> On Fri, 7 Jun 2013 17:48:59 +0200, Gregory CLEMENT wrote:
>
> > +/*
> > + * 5us delay in order to avoid repeated start
> > + * timing violation on Armada XP SoC.
> > + */
> > +static int mv64xxx_i2c_errata_delay;
>
> This should probably be a per-I2C controller variable, i.e in
> mv64xxx_i2c_data.
Yes.
>
>
> > + if (!mv64xxx_i2c_errata_delay &&
> > + of_machine_is_compatible("marvell,armadaxp"))
> > + mv64xxx_i2c_errata_delay = 1;
>
> I am wondering whether it should be done this way, or using a separate
> DT property.
Need to think about it. It is similar to the sda-hold-time issue, I
guess.