On 8/22/21 7:03 PM, Fabio M. De Francesco wrote:
On Sunday, August 22, 2021 3:31:31 PM CEST Pavel Skripkin wrote:
On 8/22/21 4:21 PM, Fabio M. De Francesco wrote:
> On Sunday, August 22, 2021 2:39:34 PM CEST Greg KH wrote:
>> On Sun, Aug 22, 2021 at 03:10:56PM +0300, Pavel Skripkin wrote:
>> > On 8/22/21 1:59 PM, Fabio M. De Francesco wrote:
>> > > On Sunday, August 22, 2021 12:09:29 PM CEST Pavel Skripkin wrote:
> [...]
>> > > So, it's up to the callers to test if (!_rtw_read*()) and then act
>> > > accordingly. If they get 0 they should know how to handle the errors.
>> >
>> > Yes, but _rtw_read*() == 0 indicates 2 states:
>> > 1. Error on transfer side
>> > 2. Actual register value is 0
>>
>> That's not a good design, it should be fixed. Note there is the new
>> usb_control_msg_recv() function which should probably be used instead
>> here, to prevent this problem from happening.
>
> I think that no functions should return 0 for signaling FAILURE. If I'm not
> wrong, the kernel quite always prefers to return 0 on SUCCESS and <0 on
> FAILURE. Why don't you just fix this?
>
That's what I've done in v2. All rtw_read* family will have following
prototype in v2:
int __must_check _rtw_read8(struct adapter *adapter, u32 addr, u8 *data);
(*)
Was it your idea, or you were talking about different approach?
With regards,
Pavel Skripkin
Pavel,
Yes, it is correct.
However, after that I had time to look at the calls chain and understand what
each function does and then I saw that my initial proposal should be made
along with another one...
The calls chain is:
(1) _rtw_read8() <--- (returns the data read from next function in chain)
(no errors returned, see possible fix in next function)
(2) usb_read8() <--- (returns the data read from next function in chain)
(_data_may_be_unitialised_, no errors returned)
(possible fix: from "u8 data"; to "char data = -1;")
Anyway char will be cast to u8 and -1 will become 0xff. 0xff is still
valid register value, I guess.
(3) usbctrl_vendorreq() <---- (returns data read from next function in chain)
(data is always a valid pointer saved to third argument)
(if it fails, the third argument is unchanged because it
still has the address of the "data" argument given by the caller) > (4) usb_control_msg() <---- (it always returns how
many bytes read or valid error codes)
(it _never_ returns 0: either positive or negative values)
I have not yet looked at the usb_control_msg_recv() which Greg talked about.
To summarize: in function (2) "u8 data" should become "char data = -1;".
So, anyway caller _should_ somehow receive an error from
usb_control_msg(). We can just change rtw_read{8,16,32} return values
from u{8,16,32} to int32, but anyway it will require all changes, that
I've done in this series, but in slightly different form. I.e temp int32
variable + error checking + casting int to u{8,16,32}.
Doesn't it make sense to just switch to more standard prototype (*)? All
other drivers use this prototype for their private reading functions.
With regards,
Pavel Skripkin
