Re: [PATCH v3 1/5] drm/rockchip: Add basic drm driver

[Daniel Vetter <daniel@ffwll.ch>]

On Mon, Sep 22, 2014 at 09:32:19AM +0800, Mark yao wrote:
> On 2014年09月20日 08:03, Rob Clark wrote:
> >On Fri, Sep 19, 2014 at 1:47 AM, Mark yao <mark.yao@rock-chips.com> wrote:
> >>diff --git a/include/uapi/drm/rockchip_drm.h b/include/uapi/drm/rockchip_drm.h
> >>new file mode 100644
> >>index 0000000..8f8e60e
> >>--- /dev/null
> >>+++ b/include/uapi/drm/rockchip_drm.h
> >>@@ -0,0 +1,97 @@
> >>+/*
> >>+ *
> >>+ * Copyright (c) Fuzhou Rockchip Electronics Co.Ltd
> >>+ * Authors:
> >>+ *       Mark Yao <yzq@rock-chips.com>
> >>+ *
> >>+ * base on exynos_drm.h
> >>+ *
> >>+ * This program is free software; you can redistribute  it and/or modify it
> >>+ * under  the terms of  the GNU General  Public License as published by the
> >>+ * Free Software Foundation;  either version 2 of the  License, or (at your
> >>+ * option) any later version.
> >>+ */
> >>+
> >>+#ifndef _UAPI_ROCKCHIP_DRM_H
> >>+#define _UAPI_ROCKCHIP_DRM_H
> >>+
> >>+#include <drm/drm.h>
> >>+
> >>+/**
> >>+ * User-desired buffer creation information structure.
> >>+ *
> >>+ * @size: user-desired memory allocation size.
> >>+ * @flags: user request for setting memory type or cache attributes.
> >>+ * @handle: returned a handle to created gem object.
> >>+ *     - this handle will be set by gem module of kernel side.
> >>+ */
> >>+struct drm_rockchip_gem_create {
> >>+       uint64_t size;
> >>+       uint32_t flags;
> >>+       uint32_t handle;
> >>+};
> >>+
> >>+/**
> >>+ * A structure for getting buffer offset.
> >>+ *
> >>+ * @handle: a pointer to gem object created.
> >>+ * @pad: just padding to be 64-bit aligned.
> >>+ * @offset: relatived offset value of the memory region allocated.
> >>+ *     - this value should be set by user.
> >>+ */
> >>+struct drm_rockchip_gem_map_off {
> >>+       uint32_t handle;
> >>+       uint32_t pad;
> >>+       uint64_t offset;
> >>+};
> >>+
> >>+/**
> >>+ * A structure for mapping buffer.
> >>+ *
> >>+ * @handle: a handle to gem object created.
> >>+ * @pad: just padding to be 64-bit aligned.
> >>+ * @size: memory size to be mapped.
> >>+ * @mapped: having user virtual address mmaped.
> >>+ *      - this variable would be filled by rockchip gem module
> >>+ *      of kernel side with user virtual address which is allocated
> >>+ *      by do_mmap().
> >>+ */
> >>+struct drm_rockchip_gem_mmap {
> >>+       uint32_t handle;
> >>+       uint32_t pad;
> >>+       uint64_t size;
> >>+       uint64_t mapped;
> >>+};
> >Could we do without the mmap ioctl?  It has been a source of problems
> >in other drivers, and the ioctl to get mmap offset, plus normal mmap()
> >on drm device file should be sufficient
> >
> >BR,
> >-R
> OK, I will try to move the special mmap ioctl and use drm generic mmap
> interface.

Actually you probably should drop all this and just implement the dummy
object support for now. Until you have proper hw accel there's no reason
to expose a driver-private gem create/mmap interface at all.

A pure kms driver really shouldn't have it's on uapi/foo_drm.h file.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch