Hello,
To complete the open reflection on this subject: to be perfect, the echo skb should in fact not be released by the USB write completion routine but, like the PCI/PCIe version, on reception in the Rx queue of an echo frame to the one written...
This means :
1 - the core of the peak_usb driver has to be deeply modified
2 - the rx path of the USB interface will be much more loaded, resulting in a higher CPU load
2 - in the case of a one-shot frame, how to manage the fact that this echo frame is never received because the one-shot frame could not be written on the bus? Does this need a garbage collector on the echo skbs?
Is it worth it?
Regards,
--- Stéphane
From: Marc Kleine-Budde
Sent: Tuesday, March 9, 2021 15:58
To: Stéphane Grosjean
Cc: Oliver Hartkopp; linux-can Mailing List
Subject: Re: [PATCH 3/3] can/peak_usb: add support of ONE_SHOT mode
On 09.03.2021 14:53:36, Stéphane Grosjean wrote:
> In the usb drivers, the echo skb is always released by the USB write
> complete callback.
This means there will be an echo_skb_get() when the USB write completes,
which is usually before the CAN controller sends the CAN frame.
This means a TX complete or an TX abort due to one shot mode will not be
reported?
regards,
Marc
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