On 16.10.2013 20:33, Michael Krufky wrote:
On Wed, Oct 16, 2013 at 1:22 PM, Antti Palosaari <crope@xxxxxx> wrote:
On 16.10.2013 20:19, Michael Krufky wrote:
On Wed, Oct 16, 2013 at 1:09 PM, Jean Delvare <khali@xxxxxxxxxxxx> wrote:
Hi Michael,
On Wed, 16 Oct 2013 13:04:42 -0400, Michael Krufky wrote:
YIKES!! i2c_new_probed_device() does indeed probe the hardware --
this is unacceptable, as such an action can damage the ic.
Is there some additional information that I'm missing that lets this
perform an attach without probe?
Oh, i2c_new_probed_device() probes the device, what a surprise! :D
Try, I don't know, i2c_new_device() maybe if you don't want the
probe? ;)
--
Jean Delvare
OK, so to confirm that I follow correctly, one can use
i2c_new_device() to attach the sub-driver without probing, and the
line that ensures that the correct sub-driver gets attached is
"strlcpy(info.type, "e4000", I2C_NAME_SIZE);" ??
We're matching based on a string? I think that's kinda yucky, but if
that's what we're doing in i2c nowadays then I'm OK with it.
If not, what prevents the wrong sub-driver from attaching to a device?
...or conversely, how does the right sub-driver know which device to
attach to?
Yes, it is that string. Driver has that string as a ID table entry. Then you
issue i2c_new_device() call with string and it attachs driver when strings
match.
Again, if I'm asking "stupid questions" just point me to the
documentation.
-Mike
regards
Antti
OK, I get it and it does seem OK. I'm just curious what kind of
impact this refactoring would have over something like the
b2c2-flexcop-fe driver, who does not know which ic's to attach based
on device ids, but it does probe a few frontend combinations one after
another, in an order that the driver authors knew was safe. I'd
imaging that we'd write some helper abstraction function to switch out
the info.type string as each driver gets probed? I think that can get
quite ugly, but I know that the general population thinks dvb_attach()
is even uglier, so maybe this could be the right path...
Wanna take a crack at b2c2-flexcop-fe?
-Mike
heh, look the rtl28xxu driver in question, it does same. It probes maybe
total 10 tuners - checking their device ID too. Probing plain I2C device
address and making devision from that is simply dead idea. "Standard"
I2C address range for these silicon tuners are 0x60-0x64 => need to read
chip ID in order to detect => i2c_new_probed_device() is quite useless.
regards
Antti
--
http://palosaari.fi/
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