Hi Michal,
On Tue, 30 Aug 2022 at 10:48, Michal Suchánek msuchanek@suse.de wrote:
On Tue, Aug 30, 2022 at 09:56:52AM -0600, Simon Glass wrote:
Hi Michal,
On Tue, 30 Aug 2022 at 04:23, Michal Suchánek msuchanek@suse.de wrote:
On Sat, Aug 27, 2022 at 07:52:27PM -0600, Simon Glass wrote:
Hi Michal,
On Fri, 19 Aug 2022 at 14:23, Michal Suchanek msuchanek@suse.de wrote:
When probing a device fails NULL pointer is returned, and other devices cannot be iterated. Skip to next device on error instead.
Fixes: 6494d708bf ("dm: Add base driver model support")
I think you should drop this as you are doing a change of behaviour, not fixing a bug!
You can hardly fix a bug without a change in behavior.
These functions are used for iterating devices, and are not iterating devices. That's clearly a bug.
If it were clear I would have changed this long ago. The new way you have this function ignores errors, so they cannot be reported.
We should almost always report errors, which is why I think your methods should be named differently.
Signed-off-by: Michal Suchanek msuchanek@suse.de
v2: - Fix up tests v3: - Fix up API doc - Correctly forward error from uclass_get - Do not return an error when last device fails to probe - Drop redundant initialization - Wrap at 80 columns
drivers/core/uclass.c | 32 ++++++++++++++++++++++++-------- include/dm/uclass.h | 13 ++++++++----- test/dm/test-fdt.c | 20 ++++++++++++++++---- 3 files changed, 48 insertions(+), 17 deletions(-)
Unfortunately this still fails one test. Try 'make qcheck' to see it - it is ethernet.
I will look at that.
I actually think you should create new functions for this feature, e.g.uclass_first_device_ok(), since it makes it impossible to see what when wrong with a device in the middle.
I have long had all this in my mind. One idea for a future change is to return the error, but set dev, so that the caller knows there is a device, which failed. When we are at the end, dev is set to NULL.
We already have uclass_first_device_check() and uclass_next_device_check() to iterate all devices, including broken ones, and getting the errors as well.
That's for the case you want all the details, and these are for the case you just want to get devices and don't care about the details.
That's AFAICT as much as this iteration interface can provide, and we have both cases covered.
I see three cases:
- want to see the next device, returning the error if it cannot be
probed - uclass_first_device()
And the point of this is what exactly?
Please can you adjust your tone, It seems too aggressive for this mailing list. Thank you.
The device order in the uclass is not well defined - at any time a new device which will become the first can be added, fail probe, and block what was assumed a loop iterating the uclass from returning any devices at all. That's exactly what happened with the new sysreset.
The order only changes if the device is unbound and rebound. Otherwise the order set by the device tree is used.
What is exactly the point of returning the error and not the pointer to the next device?
Partly, we have existing code which uses the interface, checking 'dev' to see if the device is valid. I would be happy to change that, so that the device is always returned. In fact I think it would be better. But it does need a bit of work with coccinelle, etc.
The only point of these simplified iterators is that the caller can check only one value (device pointer) and then not check the error because they don't care. If they do cate uclass_first_device_check() provides all the details available.
Yes I think we can have just two sets of iterators, but in that case it should be:
- want to see the next device, returning the error if it cannot be probed, with dev updated to the next device in any case - new version of uclass_first_device() - basically rename uclass_first_device_check() to that - want to see next device which probes OK - your new function, perhaps uclass_first_device_ok() ?
- want to get the next device that can successfully probe - your new functions
- want to see each device, along with any errors - uclass_first_device_check()
Regards, SImon