On 04/12/12 10:39, the mail apparently from Ming Lei included:
On Mon, Dec 3, 2012 at 12:52 PM, Andy Green <andy.gr...@linaro.org> wrote:
+static void ehci_hub_power_off(struct power_controller *pc, struct
device
*dev)
+{
+ gpio_set_value(GPIO_HUB_NRESET, 0);
+ gpio_set_value(GPIO_HUB_POWER, 0);
+}
+
+static struct usb_port_power_switch_data root_hub_port_data = {
+ .hub_tier = 0,
+ .port_number = 1,
+ .type = USB_PORT_CONNECT_TYPE_HARD_WIRED,
+};
+
+static struct usb_port_power_switch_data smsc_hub_port_data = {
+ .hub_tier = 1,
+ .port_number = 1,
+ .type = USB_PORT_CONNECT_TYPE_HARD_WIRED,
+};
+
+static struct power_controller pc = {
+ .name = "omap_hub_eth_pc",
+ .count = ATOMIC_INIT(0),
+ .power_on = ehci_hub_power_on,
+ .power_off = ehci_hub_power_off,
+};
+
+static inline int omap_ehci_hub_port(struct device *dev)
+{
+ /* we expect dev->parent points to ehcd controller */
+ if (dev->parent && !strcmp(dev_name(dev->parent),
"ehci-omap.0"))
+ return 1;
+ return 0;
+}
+
+static inline int dev_pc_match(struct device *dev)
+{
+ struct device *anc;
+ int ret = 0;
+
+ if (likely(strcmp(dev_name(dev), "port1")))
+ goto exit;
+
+ if (dev->parent && (anc = dev->parent->parent)) {
+ if (omap_ehci_hub_port(anc)) {
+ ret = 1;
+ goto exit;
+ }
+
+ /* is it port of lan95xx hub? */
+ if ((anc = anc->parent) && omap_ehci_hub_port(anc)) {
+ ret = 2;
+ goto exit;
+ }
+ }
+exit:
+ return ret;
+}
+
+/*
+ * Notifications of device registration
+ */
+static int device_notify(struct notifier_block *nb, unsigned long
action,
void *data)
+{
+ struct device *dev = data;
+ int ret;
+
+ switch (action) {
+ case DEV_NOTIFY_ADD_DEVICE:
+ ret = dev_pc_match(dev);
+ if (likely(!ret))
+ goto exit;
+ if (ret == 1)
+ dev_pc_bind(&pc, dev, &root_hub_port_data,
sizeof(root_hub_port_data));
+ else
+ dev_pc_bind(&pc, dev, &smsc_hub_port_data,
sizeof(smsc_hub_port_data));
+ break;
+
+ case DEV_NOTIFY_DEL_DEVICE:
+ break;
+ }
+exit:
+ return 0;
+}
+
+static struct notifier_block usb_port_nb = {
+ .notifier_call = device_notify,
+};
+
Some thoughts on trying to make this functionality specific to power only
and ehci hub port only:
- Quite a few boards have smsc95xx... they're all going to carry these
additions in the board file? Surely you'll have to generalize the pieces
All things are board dependent because we are discussing peripheral
device(not builtin SoC devices), so it is proper to put it in the board
file.
If some boards want to share it, we can put it in a single .c file and
let board file include it.
Where would the .c file go... SMSC is not platform, or even arch specific
chip (eg, iMX or MIPS or even x86 boards can have it), so not
arch/arm/mach-xxxx or arch/arm/plat-xxx or arch/arm. I guess it would go in
drivers/usb or drivers/net.
How does drivers/usb or drivers/net know the SMSC is used on beagle or
panda? Different power control approach is used in the two boards even
same SMSC chip is shipped in the two boards.
You mention you're going to "put it in a single .c file and let the
board file include it", I am just wondering where that .c file will
live. It seems it would have to live down drivers/ somewhere so MIPS,
x86 etc that might have an SMSC chip onboard can also use it if they want.
Push in ARM-Land is towards single kernels which support many platforms, a
good case in point is omap2plus_defconfg which wants to allow to support all
OMAP2/3/4/5 platforms in one kernel. If you "include" that C file over and
over in board files, it's not very nice for that. They anyway want to
eliminate board files for the single kernel binary reason, and just have one
load of config come in by dtb.
I only mean it is reasonable to put the power control code into board
file because
each board may take different power control approach even same SMSC chip
is used. I understand DT only describes the difference of the board via device
node, and I am not sure if the current DT is enough to convert the board file
into data as far as the problem is concerned.
No the approach with DT is to provide a dummy SoC "board file" with all
data provided by dtb. This is already established, see
./arch/arm/mach-omap2/board-generic.c for example. You can see there's
nothing in it other than minimum dt match business.
People with new boards are getting pointed at that and told to sort it
out in dtb and disallowed from creating new board files.
So whatever support or helper scheme you're adding needs a story about
how dtb can express it (in dt language, "has bindings for it") or it
can't be used on new boards. That's not a minor ding any more either.
So it guides you towards having static helper code once in drivers/ for the
scenarios you support... if that's where you end up smsc is less good a
target for a helper than to have helpers for classes of object like
regulator and clk, that you can combine and reuse on all sorts of target
devices, which is device_asset approach.
It also guides you to having the special platform sauce be something that
can go into the dtb: per-board code can't. That's why device_asset stuff
only places asset structs in the board file and is removing code from there.
that perform device_path business out of the omap4panda board file at
least.
At that point the path matching code becomes generic
end-of-the-device-path
matching code.
Looks Alan has mentioned, there might be no generic way, and any device's
name change in the path may make the way fragile.
What you have provided is no less fragile if you allow "port1" and the
ehci-omap.0 to be set from the outside.
Unless someone NAKs it for sure already (if you're already sure you're going
to, please do so to avoid wasting time), I'll issue a try#2 of my code later
which demonstrates what I mean. At least I guess it's useful for
comparative purposes.
- How could these literals like "port1" etc be nicely provided by
Device
Tree? In ARM-land there's pressure to eventually eliminate board files
completely and pass in everything from dtb. device_asset can neatly grow
DT
bindings in a generic way, since the footprint in the board file is some
IMO, it isn't necessary to expose these assets to device or users, from
the
view of device or user, which only cares two actions(poweron and poweroff)
about the discussed problem. Also it should be better to put these assets
into device resource list, instead of introducing them in 'struct device'.
From the point of view of allowing it to be reused on different boards /
platforms / arches, you are going to have to do something better than have
literals in the code.
regulators that already have dt bindings and some device_asset structs.
Similarly there's pressure for magic code to service a board (rather than
SoC) to go elsewhere than the board file.
Looks you associate these assets with ehci-omap device, which mightn't be
enough, because we need to control port's power for supporting port
power off mechanism. Do you have generic way to associate these assets
with usb port device and let port use it generally?
Yes, you need a parent device pointer (ehci host controller in this case)
and the path rhs, but only stuff that is defined by usb stack code. Needing
a parent pointer is OK because this stuff only has meaning for hardwired
assets on the platform, so the parent device will always be known as a
platform_device at boot time anyway.
parent device pointer may work on the panda problem, but may not work
on other case if one hardwired device is powered by another power domain.
So it is not a general solution on usb port power off.
I am talking about, well, "ancestor" pointer only to filter descendant
children. Not for any power control directly.
It gets us away from caring about what the device path looked like prior
to that host controller, and since we have confidence it's exactly the
host controller we intended by knowing its platform_device, we can
ignore everything between than at the right-hand side path fragment
identifying the child. So it's a strong way to reduce fragility on the
device_path stuff.
The code I'll provide will work the same in sdio or other bus case, just use
mmc host controller pointer and the sdio device name the same way.
- Shouldn't this take care of enabling and disabling the ULPI PHY clock
on
Panda too? There's no purpose leaving it running if the one thing the
ULPI
PHY is connected to is depowered, and when you do power it, on Panda you
will reset the ULPI PHY at the same time anyway (smsc reset and ULPI PHY
reset are connected together on Panda). Then you can eliminate
omap4_ehci_init() in the board file.
OK, we can include the ULPI PHY clock things easily in ->power_on() and
->power_off() of 'power controller'
Yes if the ARM people will accept establishing more code in board files that
doesn't have a DT story.
As I explained above, it is reasonable to put the power control code in board
file, but current DT could convert these board file into device node?
DT has lots of bindings now, you can describe regulators and things in
there fully. The point is whatever scheme is workable for this must be
able to get soaked up using DT too to be acceptable. Taking the
approach you're going to drop literal strings in code in the board file,
or throw code at the board file at all, will no longer fly.
I have not provided a DT solution for my approach yet either, but I have
taken care that the only footprint in the boardfile version of it are
*structs*. That means translating them to dtb content by adding a
binding for the asset stuff for example, will be a clean task.
That's also why back at the beginning of this discussion I gave dts
version of the regulator structs I was introducing in that patch... it's
proof that the boardfile footprint of that scheme is ready to go into dtb.
-Andy
--
Andy Green | TI Landing Team Leader
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