netdev - Re: [PATCH v2 5/6] can: c_can: prepare to up the message objects number

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Message-ID: <20210301115102.j5qwmiy2on3ezd4d@pengutronix.de>
Date:   Mon, 1 Mar 2021 12:51:02 +0100
From:   Marc Kleine-Budde <mkl@...gutronix.de>
To:     Dario Binacchi <dariobin@...ero.it>
Cc:     linux-kernel@...r.kernel.org,
        Alexander Stein <alexander.stein@...tec-electronic.com>,
        Federico Vaga <federico.vaga@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Oliver Hartkopp <socketcan@...tkopp.net>,
        Vincent Mailhol <mailhol.vincent@...adoo.fr>,
        Wolfgang Grandegger <wg@...ndegger.com>,
        YueHaibing <yuehaibing@...wei.com>,
        Zhang Qilong <zhangqilong3@...wei.com>,
        linux-can@...r.kernel.org, netdev@...r.kernel.org
Subject: Re: [PATCH v2 5/6] can: c_can: prepare to up the message objects
 number

On 28.02.2021 11:18:13, Dario Binacchi wrote:
> > > +	u32 msg_obj_rx_mask;
> > 
> > Is this variable big enough after you've extended the driver to use 64
> > mailboxes?
> 
> Yes. I have kept the message assignment policy unchanged, they are equally 
> divided between reception and transmission. Therefore, in the case of 64 
> messages, 32 are used for reception and 32 for transmission. So a 32-bit 
> variable is enough.
> 
> > 
> > If you want to support 128 message objects converting the driver to the
> > linux bitmap API is another option.
> > 
> 
> Do you know if any of the hardware managed by Linux use a D_CAN controller 
> with 128 message objects?

Even the am437x only uses 64 message objects. Ok let's stay with 64 as
max for now.

regards,
Marc

-- 
Pengutronix e.K.                 | Marc Kleine-Budde           |
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