Re: [RFC PATCH 5/5] can: m_can: Add hrtimer to generate software interrupt

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On 16.04.2023 14:33:11, Oliver Hartkopp wrote:
> 
> 
> On 4/14/23 20:20, Marc Kleine-Budde wrote:
> > On 13.04.2023 17:30:51, Judith Mendez wrote:
> > > Add a hrtimer to MCAN struct. Each MCAN will have its own
> > > hrtimer instantiated if there is no hardware interrupt found.
> > > 
> > > The hrtimer will generate a software interrupt every 1 ms. In
> > 
> > Are you sure about the 1ms?

I had the 5ms that are actually used in the code in mind. But this is a
good calculation.

> The "shortest" 11 bit CAN ID CAN frame is a Classical CAN frame with DLC = 0
> and 1 Mbit/s (arbitration) bitrate. This should be 48 bits @1Mbit => ~50
> usecs
> 
> So it should be something about
> 
>     50 usecs * (FIFO queue len - 2)

Where does the "2" come from?

> if there is some FIFO involved, right?

Yes, the mcan core has a FIFO. In the current driver the FIFO
configuration is done via device tree and fixed after that. And I don't
know the size of the available RAM in the mcan IP core on that TI SoC.

Marc

-- 
Pengutronix e.K.                 | Marc Kleine-Budde          |
Embedded Linux                   | https://www.pengutronix.de |
Vertretung Nürnberg              | Phone: +49-5121-206917-129 |
Amtsgericht Hildesheim, HRA 2686 | Fax:   +49-5121-206917-9   |

Attachment: signature.asc
Description: PGP signature


[Index of Archives]     [Device Tree Compilter]     [Device Tree Spec]     [Linux Driver Backports]     [Video for Linux]     [Linux USB Devel]     [Linux PCI Devel]     [Linux Audio Users]     [Linux Kernel]     [Linux SCSI]     [XFree86]     [Yosemite Backpacking]


  Powered by Linux