Re: [PATCH] USB-PD tcpm: bad warning+size, PPS adapters

[Greg KH <gregkh@linuxfoundation.org>]

On Sun, Dec 29, 2019 at 10:35:44PM -0500, Douglas Gilbert wrote:
> Augmented Power Delivery Objects (A)PDO_s are used by USB-C
> PD power adapters to advertize the voltages and currents
> they support. There can be up to 7 PDO_s but before PPS
> (programmable power supply) there were seldom more than 4
> or 5. Recently Samsung released an optional PPS 45 Watt power
> adapter (EP-TA485) that has 7 PDO_s. It is for the Galaxy 10+
> tablet and charges it quicker than the adapter supplied at
> purchase. The EP-TA485 causes an overzealous WARN_ON to soil
> the log plus it miscalculates the number of bytes to read.
> 
> So this bug has been there for some time but goes
> undetected for the majority of USB-C PD power adapters on
> the market today that have 6 or less PDO_s. That may soon
> change as more USB-C PD adapters with PPS come to market.
> 
> Tested on a EP-TA485 and an older Lenovo PN: SA10M13950
> USB-C 65 Watt adapter (without PPS and has 4 PDO_s) plus
> several other PD power adapters.
> 
> Signed-off-by: Douglas Gilbert <dgilbert@interlog.com>
> ---
>  drivers/usb/typec/tcpm/tcpci.c | 20 +++++++++++++++-----
>  1 file changed, 15 insertions(+), 5 deletions(-)

<formletter>

This is not the correct way to submit patches for inclusion in the
stable kernel tree.  Please read:
    https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
for how to do this properly.

</formletter>