linux-kernel - Re: [PATCH v8 4/8] drm/rockchip: dw-mipi-dsi: Fix error handling path

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Message-ID: <1552223.kPgI5s5XdI@phil>
Date:   Fri, 02 Mar 2018 13:17:16 +0100
From:   Heiko Stuebner <heiko@...ech.de>
To:     Enric Balletbo i Serra <enric.balletbo@...labora.com>
Cc:     dri-devel@...ts.freedesktop.org, Rob Herring <robh+dt@...nel.org>,
        Archit Taneja <architt@...eaurora.org>,
        Daniel Vetter <daniel.vetter@...el.com>,
        Neil Armstrong <narmstrong@...libre.com>,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        Sandy Huang <hjc@...k-chips.com>,
        linux-rockchip@...ts.infradead.org,
        Jeffy Chen <jeffy.chen@...k-chips.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v8 4/8] drm/rockchip: dw-mipi-dsi: Fix error handling path

Hi Enric,

Am Freitag, 2. März 2018, 13:09:02 CET schrieb Enric Balletbo i Serra:
> Hi Heiko,
> 
> On 01/03/18 16:50, Heiko Stübner wrote:
> > Hi Jeffy, Thierry, Enric,
> > 
> > Am Mittwoch, 10. Januar 2018, 17:23:44 CET schrieb Thierry Escande:
> >> From: Jeffy Chen <jeffy.chen@...k-chips.com>
> >>
> >> Add missing pm_runtime_disable() in bind()'s error handling path.
> >>
> >> Also cleanup encoder & connector in unbind().
> > 
> > Can you please split all these surprise "Also" sections into separate
> > patches?
> > 
> 
> I'll take a look.
> 
> > It looks like this is true for all following patch to some degree and
> > the inno-hdmi patch even has a unbind reordering-change without
> > mentioning it in the commit message.
> > 
> 
> Actually, I think this patch is not correct against current mainline, see below.
> 
> > 
> > Thanks
> > Heiko
> > 
> >> Fixes: 80a9a059d4e4 ("drm/rockchip/dsi: add dw-mipi power domain support")
> >> Signed-off-by: Jeffy Chen <jeffy.chen@...k-chips.com>
> >> Signed-off-by: Thierry Escande <thierry.escande@...labora.com>
> >> ---
> >>  drivers/gpu/drm/rockchip/dw-mipi-dsi.c | 21 +++++++++++++--------
> >>  1 file changed, 13 insertions(+), 8 deletions(-)
> >>
> >> diff --git a/drivers/gpu/drm/rockchip/dw-mipi-dsi.c
> >> b/drivers/gpu/drm/rockchip/dw-mipi-dsi.c index b1fe0639227e..78e6b7919bf7
> >> 100644
> >> --- a/drivers/gpu/drm/rockchip/dw-mipi-dsi.c
> >> +++ b/drivers/gpu/drm/rockchip/dw-mipi-dsi.c
> >> @@ -1282,7 +1282,7 @@ static int dw_mipi_dsi_bind(struct device *dev, struct
> >> device *master, ret = dw_mipi_dsi_register(drm, dsi);
> >>  	if (ret) {
> >>  		DRM_DEV_ERROR(dev, "Failed to register mipi_dsi: %d\n", ret);
> >> -		goto err_pllref;
> >> +		goto err_disable_pllref;
> >>  	}
> >>
> >>  	dsi->dsi_host.ops = &dw_mipi_dsi_host_ops;
> >> @@ -1290,24 +1290,25 @@ static int dw_mipi_dsi_bind(struct device *dev,
> >> struct device *master, ret = mipi_dsi_host_register(&dsi->dsi_host);
> >>  	if (ret) {
> >>  		DRM_DEV_ERROR(dev, "Failed to register MIPI host: %d\n", ret);
> >> -		goto err_cleanup;
> >> +		goto err_disable_pm_runtime;
> >>  	}
> >>
> >>  	if (!dsi->panel) {
> >>  		ret = -EPROBE_DEFER;
> >> -		goto err_mipi_dsi_host;
> >> +		goto err_unreg_mipi_dsi_host;
> >>  	}
> >>
> >>  	dev_set_drvdata(dev, dsi);
> >>  	pm_runtime_enable(dev);
> >>  	return 0;
> >>
> >> -err_mipi_dsi_host:
> >> +err_unreg_mipi_dsi_host:
> >>  	mipi_dsi_host_unregister(&dsi->dsi_host);
> >> -err_cleanup:
> >> -	drm_encoder_cleanup(&dsi->encoder);
> >> -	drm_connector_cleanup(&dsi->connector);
> >> -err_pllref:
> >> +err_disable_pm_runtime:
> >> +	pm_runtime_disable(dev);
> 
> I think that this is not required, 'pm_runtime_enable' is called just before the
> 'return 0' (see above). Commit 517f56839f58 'drm/rockchip: dw-mipi-dsi: fix
> possible un-balanced runtime PM enable' moved the call to that place. So, now
> the call to pm_runtime_disable is not needed.
> 
> >> +	dsi->connector.funcs->destroy(&dsi->connector);
> >> +	dsi->encoder.funcs->destroy(&dsi->encoder);
> 
> Here, there is a reordering and also a function replacement. The reorder makes
> sense to me, first cleanup the connector and then the encoder, but I'm not sure
> about the function change and if is needed, anyway, in the case is needed,
> shouldn't be
> 
> +	drm_connector_cleanup(&dsi->connector);
> +	drm_encoder_cleanup(&dsi->encoder);
> 
> instead?

If you look at drm/rockchip/dw-mipi-dsi.c you'll see that
dw_mipi_dsi_drm_connector_destroy() does both connector_unregister()
and drm_connector_cleanup().

And looking at other drivers it really seems that calling that destroy
callback is really the way to go.


Heiko