On 11/23/20 3:06 AM, Vabhav Sharma (OSS) wrote:
-----Original Message----- From: Sean Anderson seanga2@gmail.com Sent: Thursday, November 19, 2020 9:05 AM To: Vabhav Sharma (OSS) vabhav.sharma@oss.nxp.com; sjg@chromium.org; sr@denx.de Cc: u-boot@lists.denx.de; Varun Sethi V.Sethi@nxp.com; andre.przywara@arm.com; Vabhav Sharma vabhav.sharma@nxp.com Subject: Re: [PATCH v4 1/2] dm: core: add function uclass_probe_all() to probe all devices
On 11/17/20 10:00 AM, Vabhav Sharma wrote:
From: Vabhav Sharma vabhav.sharma@nxp.com
Support a common method to probe all devices associated with uclass.
This includes data structures and code for finding the first device and looping for remaining devices associated with uclasses (groups of devices with the same purpose, e.g. all SERIAL ports will be in the same
uclass).
An example is SBSA compliant PL011 UART IP, where firmware does the serial port initialization and prepare uart device to let the kernel use it for sending and reveiving the characters.SERIAL uclass will use this function to initialize PL011 UART ports.
The feature is enabled with CONFIG_DM.
Signed-off-by: Vabhav Sharma vabhav.sharma@nxp.com Reviewed-by: Stefan Roese sr@denx.de Reviewed-by: Simon Glass sjg@chromium.org -- v4: Incorporated review comments of Simon Removed if (dev).. conditional check
v3: Incorporated review comments of Stephan,Simon Related discussion https://patchwork.ozlabs.org/project/uboot/patch/1601400 385-11854-1-git-send-email-vabhav.sharma@oss.nxp.com/
drivers/core/uclass.c | 16 ++++++++++++++++ include/dm/uclass.h | 12 ++++++++++++ 2 files changed, 28 insertions(+)
diff --git a/drivers/core/uclass.c b/drivers/core/uclass.c index c3f1b73..a1dc8bb 100644 --- a/drivers/core/uclass.c +++ b/drivers/core/uclass.c @@ -792,6 +792,22 @@ int uclass_pre_remove_device(struct udevice
*dev)
} #endif
+int uclass_probe_all(enum uclass_id id) {
- struct udevice *dev;
- int ret;
- ret = uclass_first_device(id, &dev);
- if (ret || !dev)
return ret;- /* Scanning uclass to probe all devices */
- for (; dev; uclass_next_device(&dev))
You must check the return value of this function.
Error check is done for first device before passing the device to uclass_next_device(), I think of other implementation is to combine the first device check and iterating through device list of u-class as for (ret = uclass_first_device(id, &dev); dev && !ret; ret = uclass_next_device(&dev)) ; But iteration is not required if first device is not found and current changes seems to be ok Please share valuable feedback
If the second (or any device after the first) fails to init, then the error will be silently ignored.
Also, I would suggest using a while loop instead of an empty for loop.
Please elaborate, Found for loop best suitable to use here
In terms of original functionality,
while (dev) uclass_next_device(&dev)
However, I suggest
while (dev) { ret = uclass_next_device(&dev) if (ret) return ret; }
So that errors are handled properly.
;- return 0;
+}
- UCLASS_DRIVER(nop) = { .id = UCLASS_NOP, .name = "nop",
diff --git a/include/dm/uclass.h b/include/dm/uclass.h index 7188304..7ac0aaa 100644 --- a/include/dm/uclass.h +++ b/include/dm/uclass.h @@ -381,6 +381,18 @@ int uclass_first_device_drvdata(enum uclass_id id, ulong driver_data, int uclass_resolve_seq(struct udevice *dev);
/**
- uclass_probe_all() - Probe all devices based on an uclass ID
- Every uclass is identified by an ID, a number from 0 to n-1 where
- n is
- the number of uclasses. This function probe all devices asocciated
- with
nit: probes associated
Ok
- a uclass by looking its ID.
nit: for its
Sure
AFAICT uclass_find_next_device walks the linked-list of devices in a uclass, and does not care about the ID. So this documentation is incorrect.
This documentation is for new function uclass_probe_all() and understand each Uclass is identified by enum ID e.g. UCLASS_SERIAL for serial devices. According used the statement "Every uclass is identified by an ID"
Please suggest.
Ok, this documentation is confusing because the idea of uclasses being identified by their UCLASS_XXX id is a very common idea in U-Boot already. On my first reading, I thought you were instead referring to udevices being identified by id, when instead you were using udevice_get_next to get the device. I suggest documenting the method used to initialize device, and refrain from (re)documenting the method used to identify the uclass. If someone is confused about that, they need only refer to the definition of enum uclass_id.
- @id: uclass ID to look up
- @return 0 if OK, other -ve on error */ int uclass_probe_all(enum
+uclass_id id);
+/**
- uclass_id_foreach_dev() - Helper function to iteration through devices
- This creates a for() loop which works through the available
devices in