eg20t i2c driver: missing some changes?
Hi
I am using i2c-eg20t on linux 3.1.6 and comparing with the current source on
3.3-rc4
I think there is a (few) missing cleanup between the version pasted on:
http://www.spinics.net/lists/linux-i2c/msg06664.html
to the one in version 3.3-rc4
one of it is this change in pch_i2c_getack
@@ -348,7 +347,7 @@
reg_val = ioread32(p + PCH_I2CSR) & PCH_GETACK;
if (reg_val != 0) {
- pch_err(adap, "return%d\n", -EPROTO);
+ pch_dbg(adap, "return%d\n", -EPROTO);
return -EPROTO;
}
Without this change, using i2cdetect will generate a lot of false positive
errors on devices that are not present.
I'm not sure if there is a patch that is missed or still being reviewed that
contained this change
There are also some other differences between the mailing list version and
linux-3.3rc4 in addition to this one,
but I don't have enough background to comment on them.
--
Richard Retanubun
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Question on i2c->real_clk when MPC_I2C_CLOCK_PRESERVE is set
Hi Albrecht,
I am working on an MPC8360e platfrom and linux-3.0.0
I am seeing some stability issue with i2c and have some questions.
In git commit "powerpc/5200/i2c: improve i2c bus error recovery"
0c2daaafcdec726e89cbccca61d576de8429c537
The concept of i2c->real_clk is introduced to better optimize mpc_i2c_fixup().
Unless I am mistaken, in the current implementation, when
MPC_I2C_CLOCK_PRESERVE is set,
i2c->real_clk is never initialized.
So lets presume that its value is likely 0.
That makes mpc_i2c_fixup() look like this:
int k;
u32 delay_val = 100 / i2c->real_clk + 1; /* delay_val = 100 */
if (delay_val < 2)
delay_val = 2;
for (k = 9; k; k--) {
writeccr(i2c, 0);
writeccr(i2c, CCR_MSTA | CCR_MTX | CCR_MEN);
udelay(delay_val); /* 100us = 1 sec */
writeccr(i2c, CCR_MEN);
udelay(delay_val << 1); /* 200 = 2 sec */
}
Which I think is not the intended value, no?
I tried to see if I can populate i2c->real_clk using the preserved values
inside fdr and dfsrr
but I don't think that's possible without a lookup table (or another dts
binding)
The other thought I have to in addition of a mininum delay_val of 2, we can
also add a maximum limit
for delay_val (of 30us ? to maintain the delay of the previous version)
As an aside, uboot seems to have a way to figure out the correct values of fdr
and dfsrr without lookup
/drivers/i2c/fsl-i2c.c::set_i2c_bus_speed(). This will prevent needing to use
MPC_I2C_CLOCK_PRESERVE
and get i2c->real_clk calculated properly.
Thanks for your time.
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Richard Retanubun
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Re: [i2c-mpc.c] adding entry for mpc8360
On 13/01/12 02:26 AM, Wolfgang Grandegger wrote:
Hello,
I added the "devicetree-discuss" ml.
On 01/12/2012 04:34 PM, Richard Retanubun wrote:
Hello,
I am wondering if it is okay to add .compatible entries for mpc8360 and
declare its data structure
to mpc-i2c.c
something like this:
{.compatible = "fsl,mpc8360-i2c", .data =&mpc_i2c_data_8360, },
static struct mpc_i2c_data mpc_i2c_data_8360 __devinitdata = {
.setup = mpc_i2c_setup_8xxx,
};
or is the intended approach to match the closest thing to your CPU (in
this case mpc8313) ?
Yes, it is intended to use the name of the compatible device, see:
http://lxr.linux.no/#linux+v3.2.1/arch/powerpc/boot/dts/kmeter1.dts#L69
Wolfgang
Thanks for the speedy response!
Two observations based on recent experiments to share with the ml:
1. The i2c-mpc does not take into account freescale APP note AN2919
and for boards where the default dfsr setting violates condition #1.
the i2c_transfer will exit with a -EIO due to timeout once in a while.
2. For boards that uses u-boot as bootloader, its fsl-i2c driver implements
condition #1 checking. Thus using fsl,preserve-clocking is the way to go
for now.
Richard
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[i2c-mpc.c] adding entry for mpc8360
Hello,
I am wondering if it is okay to add .compatible entries for mpc8360 and declare
its data structure
to mpc-i2c.c
something like this:
{.compatible = "fsl,mpc8360-i2c", .data = &mpc_i2c_data_8360, },
static struct mpc_i2c_data mpc_i2c_data_8360 __devinitdata = {
.setup = mpc_i2c_setup_8xxx,
};
or is the intended approach to match the closest thing to your CPU (in this
case mpc8313) ?
--
Richard Retanubun
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