netdev - RE: [PATCH v3 1/2] can: m_can: Move mram init to mcan device setup

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Date:   Thu, 24 Nov 2022 14:36:48 +0530
From:   "Vivek Yadav" <vivek.2311@...sung.com>
To:     "'Marc Kleine-Budde'" <mkl@...gutronix.de>
Cc:     <rcsekar@...sung.com>, <krzysztof.kozlowski+dt@...aro.org>,
        <wg@...ndegger.com>, <davem@...emloft.net>, <edumazet@...gle.com>,
        <kuba@...nel.org>, <pabeni@...hat.com>, <pankaj.dubey@...sung.com>,
        <ravi.patel@...sung.com>, <alim.akhtar@...sung.com>,
        <linux-fsd@...la.com>, <robh+dt@...nel.org>,
        <linux-can@...r.kernel.org>, <netdev@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-samsung-soc@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <aswani.reddy@...sung.com>, <sriranjani.p@...sung.com>
Subject: RE: [PATCH v3 1/2] can: m_can: Move mram init to mcan device setup



> -----Original Message-----
> From: Marc Kleine-Budde <mkl@...gutronix.de>
> Sent: 24 November 2022 04:12
> To: Vivek Yadav <vivek.2311@...sung.com>
> Cc: rcsekar@...sung.com; krzysztof.kozlowski+dt@...aro.org;
> wg@...ndegger.com; davem@...emloft.net; edumazet@...gle.com;
> kuba@...nel.org; pabeni@...hat.com; pankaj.dubey@...sung.com;
> ravi.patel@...sung.com; alim.akhtar@...sung.com; linux-fsd@...la.com;
> robh+dt@...nel.org; linux-can@...r.kernel.org; netdev@...r.kernel.org;
> linux-kernel@...r.kernel.org; linux-arm-kernel@...ts.infradead.org; linux-
> samsung-soc@...r.kernel.org; devicetree@...r.kernel.org;
> aswani.reddy@...sung.com; sriranjani.p@...sung.com
> Subject: Re: [PATCH v3 1/2] can: m_can: Move mram init to mcan device
> setup
> 
> On 22.11.2022 16:24:54, Vivek Yadav wrote:
> > When we try to access the mcan message ram addresses, hclk is gated by
> > any other drivers or disabled, because of that probe gets failed.
> >
> > Move the mram init functionality to mcan device setup called by mcan
> > class register from mcan probe function, by that time clocks are
> > enabled.
> 
> Why not call the RAM init directly from m_can_chip_config()?
> 
m_can_chip_config function is called from m_can open.

Configuring RAM init every time we open the CAN instance is not needed, I think only once during the probe is enough. 

If message RAM init failed then fifo Transmit and receive will fail and there will be no communication. So there is no point to "open and Configure CAN chip".

From my understanding it's better to keep RAM init inside the probe and if there is a failure happened goes to CAN probe failure.
> Marc
Thanks for reviewing the patch.
> 
> --
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