[PATCH v2 03/10] drm/hisilicon: Add hisilicon DRM master driver

[Emil Velikov]

Hi Xinliang,

On 28 November 2015 at 10:38, Xinliang Liu <xinliang.liu at linaro.org> wrote:
> Add DRM master driver for hi6220 SoC which used in HiKey board.
> Add dumb buffer feature.
> Add prime dmabuf feature.
>
> Signed-off-by: Xinliang Liu <xinliang.liu at linaro.org>
> Signed-off-by: Xinwei Kong <kong.kongxinwei at hisilicon.com>
> Signed-off-by: Andy Green <andy.green at linaro.org>
Your s-o-b should be the bottom of the list. There was a presentation
(ages ago) from Greg KH, who nicely described the order as a "chain of
command" or "guilt path". Looks like the rest of the series could use
this tweak.

> ---
>  drivers/gpu/drm/Kconfig                  |   2 +
>  drivers/gpu/drm/Makefile                 |   1 +
>  drivers/gpu/drm/hisilicon/Kconfig        |   9 ++
>  drivers/gpu/drm/hisilicon/Makefile       |   3 +
>  drivers/gpu/drm/hisilicon/hisi_drm_drv.c | 214 +++++++++++++++++++++++++++++++
>  5 files changed, 229 insertions(+)
>  create mode 100644 drivers/gpu/drm/hisilicon/Kconfig
>  create mode 100644 drivers/gpu/drm/hisilicon/Makefile
>  create mode 100644 drivers/gpu/drm/hisilicon/hisi_drm_drv.c
>
> diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
> index 8773fad..038aae8 100644
> --- a/drivers/gpu/drm/Kconfig
> +++ b/drivers/gpu/drm/Kconfig
> @@ -274,3 +274,5 @@ source "drivers/gpu/drm/amd/amdkfd/Kconfig"
>  source "drivers/gpu/drm/imx/Kconfig"
>
>  source "drivers/gpu/drm/vc4/Kconfig"
> +
> +source "drivers/gpu/drm/hisilicon/Kconfig"
I could swear that we can a patch that sorts these alphabetically,
although it doesn't seem to have made it upstream yet :-(

> --- /dev/null
> +++ b/drivers/gpu/drm/hisilicon/hisi_drm_drv.c

> +static int hisi_drm_load(struct drm_device *dev, unsigned long flags)
> +{
The use of .load (and .unload?) callbacks is not recommended. Take a
look at Laurent Pinchart's patch [1] about the whys and hows on the
topic

> +static struct dma_buf *hisi_gem_prime_export(struct drm_device *dev,
> +                                            struct drm_gem_object *obj,
> +                                            int flags)
> +{
> +       /* we want to be able to write in mmapped buffer */
> +       flags |= O_RDWR;
Erm... something feels fishy here. Out of the existing 15 drivers
setting up the prime callbacks only one (sti) does a similar thing. So
either everyone else is missing something obvious or hisilicon and sti
can rework their inner working to remove this (dare I say it) hack.

> +static int hisi_gem_cma_dumb_create(struct drm_file *file,
> +                                   struct drm_device *dev,
> +                                   struct drm_mode_create_dumb *args)
> +{
> +       int min_pitch = DIV_ROUND_UP(args->width * args->bpp, 8);
> +
> +       /* mali gpu need pitch 8 bytes alignment for 32bpp */
> +       args->pitch = roundup(min_pitch, 8);
> +
I'm not sure you want this kind of dependency of an out of tree driver
upstream. If this is some limitation on the display engine so be it,
but tailoring things for an external module seems like a very bad
idea.

> +       return drm_gem_cma_dumb_create_internal(file, dev, args);
> +}

> +static int hisi_drm_bind(struct device *dev)
> +{
> +       dma_set_coherent_mask(dev, DMA_BIT_MASK(32));
> +       return drm_platform_init(&hisi_drm_driver, to_platform_device(dev));
As pointed out by the the kernel doc - drm_platform_init is deprecated.


Regards,
Emil

[1] http://lists.freedesktop.org/archives/dri-devel/2015-November/095466.html