linux-kernel - Re: [PATCH v4] drm/bochs: add drm

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Message-ID: <20200211141956.GC2363188@phenom.ffwll.local>
Date:   Tue, 11 Feb 2020 15:19:56 +0100
From:   Daniel Vetter <daniel@...ll.ch>
To:     Gerd Hoffmann <kraxel@...hat.com>
Cc:     dri-devel@...ts.freedesktop.org, daniel@...ll.ch,
        David Airlie <airlied@...ux.ie>,
        "open list:DRM DRIVER FOR BOCHS VIRTUAL GPU" 
        <virtualization@...ts.linux-foundation.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v4] drm/bochs: add drm_driver.release callback.

On Tue, Feb 11, 2020 at 02:52:18PM +0100, Gerd Hoffmann wrote:
> Call bochs_unload via drm_driver.release to make sure we release stuff
> when it is safe to do so.  Use drm_dev_{enter,exit,unplug} to avoid
> touching hardware after device removal.  Tidy up here and there.
> 
> v4: add changelog.
> v3: use drm_dev_*().
> v2: move hardware deinit to pci_remove().
> 
> Signed-off-by: Gerd Hoffmann <kraxel@...hat.com>

Reviewed-by: Daniel Vetter <daniel.vetter@...ll.ch>

Btw I checked around whether there's anything else that obviously needs a
drm_dev_enter/exit, and I spotted the !bochs->mmio check in
bochs_hw_load_edid. That one looks like cargo-cult, there's a single
caller in the init path, so either mmio works at that point or this is
dead code ... slightly confusing.
-Daniel

> ---
>  drivers/gpu/drm/bochs/bochs_drv.c |  6 +++---
>  drivers/gpu/drm/bochs/bochs_hw.c  | 24 +++++++++++++++++++++++-
>  2 files changed, 26 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/bochs/bochs_drv.c b/drivers/gpu/drm/bochs/bochs_drv.c
> index 10460878414e..addb0568c1af 100644
> --- a/drivers/gpu/drm/bochs/bochs_drv.c
> +++ b/drivers/gpu/drm/bochs/bochs_drv.c
> @@ -23,7 +23,6 @@ static void bochs_unload(struct drm_device *dev)
>  
>  	bochs_kms_fini(bochs);
>  	bochs_mm_fini(bochs);
> -	bochs_hw_fini(dev);
>  	kfree(bochs);
>  	dev->dev_private = NULL;
>  }
> @@ -69,6 +68,7 @@ static struct drm_driver bochs_driver = {
>  	.major			= 1,
>  	.minor			= 0,
>  	DRM_GEM_VRAM_DRIVER,
> +	.release                = bochs_unload,
>  };
>  
>  /* ---------------------------------------------------------------------- */
> @@ -148,9 +148,9 @@ static void bochs_pci_remove(struct pci_dev *pdev)
>  {
>  	struct drm_device *dev = pci_get_drvdata(pdev);
>  
> +	drm_dev_unplug(dev);
>  	drm_atomic_helper_shutdown(dev);
> -	drm_dev_unregister(dev);
> -	bochs_unload(dev);
> +	bochs_hw_fini(dev);
>  	drm_dev_put(dev);
>  }
>  
> diff --git a/drivers/gpu/drm/bochs/bochs_hw.c b/drivers/gpu/drm/bochs/bochs_hw.c
> index b615b7dfdd9d..952199cc0462 100644
> --- a/drivers/gpu/drm/bochs/bochs_hw.c
> +++ b/drivers/gpu/drm/bochs/bochs_hw.c
> @@ -4,6 +4,7 @@
>  
>  #include <linux/pci.h>
>  
> +#include <drm/drm_drv.h>
>  #include <drm/drm_fourcc.h>
>  
>  #include "bochs.h"
> @@ -194,6 +195,8 @@ void bochs_hw_fini(struct drm_device *dev)
>  {
>  	struct bochs_device *bochs = dev->dev_private;
>  
> +	/* TODO: shot down existing vram mappings */
> +
>  	if (bochs->mmio)
>  		iounmap(bochs->mmio);
>  	if (bochs->ioports)
> @@ -207,6 +210,11 @@ void bochs_hw_fini(struct drm_device *dev)
>  void bochs_hw_setmode(struct bochs_device *bochs,
>  		      struct drm_display_mode *mode)
>  {
> +	int idx;
> +
> +	if (!drm_dev_enter(bochs->dev, &idx))
> +		return;
> +
>  	bochs->xres = mode->hdisplay;
>  	bochs->yres = mode->vdisplay;
>  	bochs->bpp = 32;
> @@ -232,11 +240,18 @@ void bochs_hw_setmode(struct bochs_device *bochs,
>  
>  	bochs_dispi_write(bochs, VBE_DISPI_INDEX_ENABLE,
>  			  VBE_DISPI_ENABLED | VBE_DISPI_LFB_ENABLED);
> +
> +	drm_dev_exit(idx);
>  }
>  
>  void bochs_hw_setformat(struct bochs_device *bochs,
>  			const struct drm_format_info *format)
>  {
> +	int idx;
> +
> +	if (!drm_dev_enter(bochs->dev, &idx))
> +		return;
> +
>  	DRM_DEBUG_DRIVER("format %c%c%c%c\n",
>  			 (format->format >>  0) & 0xff,
>  			 (format->format >>  8) & 0xff,
> @@ -256,13 +271,18 @@ void bochs_hw_setformat(struct bochs_device *bochs,
>  			  __func__, format->format);
>  		break;
>  	}
> +
> +	drm_dev_exit(idx);
>  }
>  
>  void bochs_hw_setbase(struct bochs_device *bochs,
>  		      int x, int y, int stride, u64 addr)
>  {
>  	unsigned long offset;
> -	unsigned int vx, vy, vwidth;
> +	unsigned int vx, vy, vwidth, idx;
> +
> +	if (!drm_dev_enter(bochs->dev, &idx))
> +		return;
>  
>  	bochs->stride = stride;
>  	offset = (unsigned long)addr +
> @@ -277,4 +297,6 @@ void bochs_hw_setbase(struct bochs_device *bochs,
>  	bochs_dispi_write(bochs, VBE_DISPI_INDEX_VIRT_WIDTH, vwidth);
>  	bochs_dispi_write(bochs, VBE_DISPI_INDEX_X_OFFSET, vx);
>  	bochs_dispi_write(bochs, VBE_DISPI_INDEX_Y_OFFSET, vy);
> +
> +	drm_dev_exit(idx);
>  }
> -- 
> 2.18.2
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch