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Date: Wed, 31 Aug 2011 16:33:30 +0900
From: Inki Dae <inki.dae@...sung.com>
To: 'Konrad Rzeszutek Wilk' <konrad.wilk@...cle.com>,
'Rob Clark' <robdclark@...il.com>
Cc: sw0312.kim@...sung.com, linux-kernel@...r.kernel.org,
dri-devel@...ts.freedesktop.org, kyungmin.park@...sung.com,
linux-arm-kernel@...ts.infradead.org
Subject: RE: [RFC][PATCH v3] DRM: add DRM Driver for Samsung SoC EXYNOS4210.
Hello, Konrad Rzeszutek Wilk.
> -----Original Message-----
> From: Konrad Rzeszutek Wilk [mailto:konrad.wilk@...cle.com]
> Sent: Wednesday, August 31, 2011 11:07 AM
> To: Rob Clark
> Cc: Inki Dae; sw0312.kim@...sung.com; linux-kernel@...r.kernel.org; dri-
> devel@...ts.freedesktop.org; kyungmin.park@...sung.com; linux-arm-
> kernel@...ts.infradead.org
> Subject: Re: [RFC][PATCH v3] DRM: add DRM Driver for Samsung SoC
> EXYNOS4210.
>
> > > + entry->vaddr = dma_alloc_writecombine(dev->dev, entry->size,
> > > + (dma_addr_t *)&entry->paddr, GFP_KERNEL);
> > > + if (!entry->paddr) {
> > > + DRM_ERROR("failed to allocate buffer.\n");
> > > + return -ENOMEM;
> > > + }
> > > +
> > > + DRM_DEBUG_KMS("allocated : vaddr(0x%x), paddr(0x%x),
> size(0x%x)\n",
> > > + (unsigned int)entry->vaddr, entry->paddr,
entry-
> >size);
> > > +
> > > + return 0;
> > > +}
> > > +
> > [snip]
> >
> > > diff --git a/drivers/gpu/drm/samsung/samsung_drm_buf.h
> b/drivers/gpu/drm/samsung/samsung_drm_buf.h
> > > new file mode 100644
> > > index 0000000..d6a7e95
> > > --- /dev/null
> > > +++ b/drivers/gpu/drm/samsung/samsung_drm_buf.h
> > [snip]
> > > +/**
> > > + * samsung drm buffer entry structure.
> > > + *
> > > + * @paddr: physical address of allocated memory.
> > > + * @vaddr: kernel virtual address of allocated memory.
> > > + * @size: size of allocated memory.
> > > + */
> > > +struct samsung_drm_buf_entry {
> > > + unsigned int paddr;
>
> This could be made 'dma_addr_t' and then you can drop all of the
> casts to (dma_addr_t *).
>
Ok, I will correct it right now. thank you.
> .. snip..
> > > +static int samsung_drm_connector_get_modes(struct drm_connector
> *connector)
>
> Why not make the return be 'unsigned int'?
>
Yes, I think so, but please, see drm_connector_helper_funcs structure of
drm_crtc_helper.h. get_modes callback has int type as return.
> .. snip..
> > > +/* get detection status of display device. */
> > > +static enum drm_connector_status
> > > +samsung_drm_connector_detect(struct drm_connector *connector, bool
> force)
> > > +{
> > > + struct samsung_drm_connector *samsung_connector =
> > > + to_samsung_connector(connector);
> > > + struct samsung_drm_display *display =
> > > + samsung_drm_get_manager(samsung_connector->encoder)-
> >display;
> > > + unsigned int ret = connector_status_unknown;
>
> Not 'enum drm_connector_status ret = connector_status_unknown' ?
>
Oh, you are right, I will fix up it. thank you.
> > > +
> > > + DRM_DEBUG_KMS("%s\n", __FILE__);
> > > +
> > > + if (display && display->is_connected) {
> > > + if (display->is_connected())
> > > + ret = connector_status_connected;
> > > + else
> > > + ret = connector_status_disconnected;
> > > + }
> > > +
> > > + return ret;
> > > +}
>
> .. snip..
> > > +static void samsung_drm_fb_destroy(struct drm_framebuffer *fb)
> > > +{
> > > + struct samsung_drm_fb *samsung_fb = to_samsung_fb(fb);
> > > + int ret;
>
> Get rid of 'ret'
It seems that it doesn't need 'ret' but it needs to check 'ret' because of
drm_gem_handle_delete().
> > > +
> > > + DRM_DEBUG_KMS("%s\n", __FILE__);
> > > +
> > > + drm_framebuffer_cleanup(fb);
> > > +
> > > + if (samsung_fb->is_default) {
> > > + ret = drm_gem_handle_delete(samsung_fb->file_priv,
> > > + samsung_fb->gem_handle);
> >
> > why not keep the gem buffer ptr, and do something like:
> >
> > drm_gem_object_unreference_unlocked(samsung_fb->bo)..
> >
> > this way, you get the right behavior if someone somewhere else took a
> > ref to the gem buffer object? And it avoids needing to keep the
> > file_priv ptr in the fb (which seems a bit strange)
> >
> >
> > > + if (ret < 0)
> > > + DRM_ERROR("failed to delete
drm_gem_handle.\n");
>
> And just do the check on the function return value here. You are not using
> the 'ret' for anything.
Yes, right. it just prints out error message because drm_gem_handle_delete
function which is mainline function doesn't leave any error message. anyway
using 'ret' is not clear. so I will remove 'ret' and check
drm_gem_handle_delete function directly instead to print out error message.
> > > + }
> > > +
> > > + kfree(samsung_fb);
> > > +}
> > > +
> > [snip]
>
> Hm, so I stopped here - just realized that I am missing some of the code
> and I should look at the original patch..
Thank you for your comments. it's been very useful. please give me your
comments and advices anytime then I will be pleased.
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