linux-kernel - Re: [PATCH 03/10] remoteproc: imx: use devm

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Message-ID: <20200727064151.767kc7622tcqmqfs@pengutronix.de>
Date:   Mon, 27 Jul 2020 08:41:51 +0200
From:   Oleksij Rempel <o.rempel@...gutronix.de>
To:     Peng Fan <peng.fan@....com>
Cc:     "bjorn.andersson@...aro.org" <bjorn.andersson@...aro.org>,
        "mathieu.poirier@...aro.org" <mathieu.poirier@...aro.org>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "linux-remoteproc@...r.kernel.org" <linux-remoteproc@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "shawnguo@...nel.org" <shawnguo@...nel.org>,
        "s.hauer@...gutronix.de" <s.hauer@...gutronix.de>,
        "kernel@...gutronix.de" <kernel@...gutronix.de>,
        "festevam@...il.com" <festevam@...il.com>,
        dl-linux-imx <linux-imx@....com>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>
Subject: Re: [PATCH 03/10] remoteproc: imx: use devm_ioremap

On Mon, Jul 27, 2020 at 06:28:20AM +0000, Peng Fan wrote:
> Hi Oleksij,
> 
> > Subject: Re: [PATCH 03/10] remoteproc: imx: use devm_ioremap
> > 
> > On Fri, Jul 24, 2020 at 04:08:06PM +0800, Peng Fan wrote:
> > > We might need to map an region multiple times, becaue the region might
> > > be shared between remote processors, such i.MX8QM with dual M4 cores.
> > > So use devm_ioremap, not devm_ioremap_resource.
> > 
> > Can you please give an example of this kind of shared resources and how they
> > should be handled by two separate devices?
> 
> This is to share vdevbuffer space, there is a vdevbuffer in device tree, it will be
> shared between M4_0 and M4_1.
>
> For the buffer, it is Linux DMA API will handle the space.

Why remoteproc need to care about it? If I see it correctly, from the
linux perspective, it is one buffer and one driver is responsible for
it. Or do I missing some thing?

> Thanks,
> Peng.
> 
> > 
> > > Reviewed-by: Richard Zhu <hongxing.zhu@....com>
> > > Signed-off-by: Peng Fan <peng.fan@....com>
> > > ---
> > >  drivers/remoteproc/imx_rproc.c | 5 +++--
> > >  1 file changed, 3 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/drivers/remoteproc/imx_rproc.c
> > > b/drivers/remoteproc/imx_rproc.c index 3b3904ebac75..82594a800a1b
> > > 100644
> > > --- a/drivers/remoteproc/imx_rproc.c
> > > +++ b/drivers/remoteproc/imx_rproc.c
> > > @@ -296,9 +296,10 @@ static int imx_rproc_addr_init(struct imx_rproc
> > *priv,
> > >  		if (b >= IMX7D_RPROC_MEM_MAX)
> > >  			break;
> > >
> > > -		priv->mem[b].cpu_addr = devm_ioremap_resource(&pdev->dev,
> > &res);
> > > +		/* Not use resource version, because we might share region*/
> > > +		priv->mem[b].cpu_addr = devm_ioremap(&pdev->dev, res.start,
> > > +resource_size(&res));
> > >  		if (IS_ERR(priv->mem[b].cpu_addr)) {
> > > -			dev_err(dev, "devm_ioremap_resource failed\n");
> > > +			dev_err(dev, "devm_ioremap %pR failed\n", &res);
> > >  			err = PTR_ERR(priv->mem[b].cpu_addr);
> > >  			return err;
> > >  		}
> > > --
> > > 2.16.4
> > >
> > >
> > 
> > --
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> > |
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