On Sun, Sep 18, 2011 at 3:31 PM, Thomas Hellstrom thomas@shipmail.org wrote:
On 09/18/2011 10:15 PM, Rob Clark wrote:
On Sun, Sep 18, 2011 at 3:00 PM, Thomas Hellstromthomas@shipmail.org wrote:
On 09/18/2011 09:50 PM, Rob Clark wrote:
On Sun, Sep 18, 2011 at 2:36 PM, Thomas Hellstromthomas@shipmail.org wrote:
On 09/17/2011 11:32 PM, Rob Clark wrote:
From: Rob Clarkrob@ti.com
A DRM display driver for TI OMAP platform. Similar to omapfb (fbdev) and omap_vout (v4l2 display) drivers in the past, this driver uses the DSS2 driver to access the display hardware, including support for HDMI, DVI, and various types of LCD panels. And it implements GEM support for buffer allocation (for KMS as well as offscreen buffers used by the xf86-video-omap userspace xorg driver).
The driver maps CRTCs to overlays, encoders to overlay-managers, and connectors to dssdev's. Note that this arrangement might change slightly when support for drm_plane overlays is added.
For GEM support, non-scanout buffers are using the shmem backed pages provided by GEM core (In drm_gem_object_init()). In the case of scanout buffers, which need to be physically contiguous, those are allocated with CMA and use drm_gem_private_object_init().
See userspace xorg driver: git://github.com/robclark/xf86-video-omap.git
Refer to this link for CMA (Continuous Memory Allocator): http://lkml.org/lkml/2011/8/19/302
Links to previous versions of the patch: v1: http://lwn.net/Articles/458137/
History:
v2: replace omap_vram with CMA for scanout buffer allocation, remove unneeded functions, use dma_addr_t for physical addresses, error handling cleanup, refactor attach/detach pages into common drm functions, split non-userspace-facing API into omap_priv.h, remove plugin API
v1: original
drivers/staging/Kconfig | 2 + drivers/staging/Makefile | 1 + drivers/staging/omapdrm/Kconfig | 24 + drivers/staging/omapdrm/Makefile | 9 + drivers/staging/omapdrm/TODO.txt | 14 + drivers/staging/omapdrm/omap_connector.c | 357 ++++++++++++++ drivers/staging/omapdrm/omap_crtc.c | 332 +++++++++++++ drivers/staging/omapdrm/omap_drv.c | 766 ++++++++++++++++++++++++++++++ drivers/staging/omapdrm/omap_drv.h | 126 +++++ drivers/staging/omapdrm/omap_encoder.c | 188 ++++++++ drivers/staging/omapdrm/omap_fb.c | 259 ++++++++++ drivers/staging/omapdrm/omap_fbdev.c | 309 ++++++++++++ drivers/staging/omapdrm/omap_gem.c | 720 ++++++++++++++++++++++++++++ drivers/video/omap2/omapfb/Kconfig | 2 +- include/drm/Kbuild | 1 + include/drm/omap_drm.h | 111 +++++ include/drm/omap_priv.h | 42 ++ 17 files changed, 3262 insertions(+), 1 deletions(-) create mode 100644 drivers/staging/omapdrm/Kconfig create mode 100644 drivers/staging/omapdrm/Makefile create mode 100644 drivers/staging/omapdrm/TODO.txt create mode 100644 drivers/staging/omapdrm/omap_connector.c create mode 100644 drivers/staging/omapdrm/omap_crtc.c create mode 100644 drivers/staging/omapdrm/omap_drv.c create mode 100644 drivers/staging/omapdrm/omap_drv.h create mode 100644 drivers/staging/omapdrm/omap_encoder.c create mode 100644 drivers/staging/omapdrm/omap_fb.c create mode 100644 drivers/staging/omapdrm/omap_fbdev.c create mode 100644 drivers/staging/omapdrm/omap_gem.c create mode 100644 include/drm/omap_drm.h create mode 100644 include/drm/omap_priv.h
...
diff --git a/include/drm/omap_drm.h b/include/drm/omap_drm.h new file mode 100644 index 0000000..ea0ae8e --- /dev/null +++ b/include/drm/omap_drm.h @@ -0,0 +1,111 @@ +/*
- linux/include/drm/omap_drm.h
- Copyright (C) 2011 Texas Instruments
- Author: Rob Clarkrob@ti.com
- This program is free software; you can redistribute it and/or
modify it
- under the terms of the GNU General Public License version 2 as
published by
- the Free Software Foundation.
- This program is distributed in the hope that it will be useful,
but WITHOUT
- ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
or
- FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
License for
- more details.
- You should have received a copy of the GNU General Public License
along with
- this program. If not, seehttp://www.gnu.org/licenses/.
- */
+#ifndef __OMAP_DRM_H__ +#define __OMAP_DRM_H__
+#include "drm.h"
+/* Please note that modifications to all structs defined here are
- subject to backwards-compatibility constraints.
- */
+#define OMAP_PARAM_CHIPSET_ID 1 /* ie. 0x3430, 0x4430, etc */
+struct drm_omap_param {
- uint64_t param; /* in */
- uint64_t value; /* in (set_param), out
(get_param) */ +};
+struct drm_omap_get_base {
- char plugin_name[64]; /* in */
- uint32_t ioctl_base; /* out */
+};
What about future ARM 64-bit vs 32-bit structure sizes? On x86 we always take care to make structures appearing in the drm user-space interfaces having sizes that are a multiple of 64-bits, to avoid having to maintain compat code for 32-bit apps running on 64 bit kernels. For the same reasons, structure members with 64 bit alignment requirements on 64-bit systems need to be carefully places.
I don't know whether there is or will be a 64-bit ARM, but it might be worth taking into consideration.
There isn't currently any 64-bit ARM, but it is a safe assumption that there will be some day.. I guess we'll have enough fun w/ various random 32b devices when LPAE arrives w/ the cortex-a15..
I did try to make sure any uint64_t's were aligned to a 64bit offset, but beyond that I confess to not being an expert on how 64 vs 32b ioctl compat stuff is handled or what the issues going from 32->64b are. If there are some additional considerations that should be taken care of, then now is the time. So far I don't have any pointer fields in any of the ioctl structs. Beyond that, I'm not entirely sure what else needs to be done, but would appreciate any pointers to docs about how the compat stuff works.
BR, -R
I've actually avoided writing compat ioctl code myself, by trying to make sure that structures look identical in the 64-bit and 32-bit x86 ABIs, but the compat code is there to translate pointers and to overcome alignment incompatibilities.
A good way to at least try to avoid having to maintain compat code once the 64-bit ABI shows up is to make sure that 64-bit scalars and embedded structures are placed on 64-bit boundaries, padding if necessary, and to make sure (using padding) that struct sizes are always multiples of 64 bits.
So far this is true for 64bit scalars.. I'm using stdint types everywhere so there is no chance for fields having different sizes on 64b vs 32b. And the only structs contained within ioctl structs so far are starting at offset==0.
Is it necessary to ensure that the ioctl structs themselves (as opposed to structs within those structs) have sizes that are multiple of 64b? The ioctl structs are copied (copy_from_user()/copy_to_user()), which I would have assumed would be sufficient?
It depends. If a 64 bit kernel calculates the size as sizeof(struct ...) and then tries to copy it to user-space using copy_to_user(), it might want to copy more than the user-space structure size, causing -EFAULTs or overwritten user-space data. (If user-space is 32-bit.)
On x86, for example
struct { int64_t a; int32_t b; } x;
Is 96 byte in the 32 bit ABI, but 128 byte in the 64-bit ABI. So if you issue
copy_to_user(user_ptr, &x, sizeof(x))
It will try to copy 128 byte on a 64-bit kernel and will overwrite data or cause segfault with a 32-bit user-space.
However, IIRC the drm ioctl copy code uses the size encoded by user-space, which avoids that problem, but that's an implementation specific feature that shouldn't be relied upon.
Ok, gotcha, thx for the explaination.. I'll add a couple of pad fields where needed
BR, -R
/Thomas
But since there is no 64-bit ARM yet, it might be better to rely on using compat code in the future than on making guesses about alignment restrictions of the ABI...
hmm, it might be nice to get some guidelines from ARM on this, since I really have no idea what a 64b ARM architecture would look like..
BR, -R
/Thomas
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