Re: [PATCH] omap2+: add drm device

[Rob Clark <rob.clark@linaro.org>]

On Tue, Mar 6, 2012 at 7:26 AM, Tomi Valkeinen <tomi.valkeinen@ti.com> wrote:
> On Mon, 2012-03-05 at 10:54 -0600, Rob Clark wrote:
>> From: Andy Gross <andy.gross@ti.com>
>>
>> Register OMAP DRM/KMS platform device, and reserve a CMA region for
>> the device to use for buffer allocation.  DMM is split into a
>> separate device using hwmod.
>>
>> Signed-off-by: Andy Gross <andy.gross@ti.com>
>> Signed-off-by: Rob Clark <rob@ti.com>
>> ---
>>  arch/arm/plat-omap/Makefile           |    2 +-
>>  arch/arm/plat-omap/common.c           |    3 +-
>>  arch/arm/plat-omap/drm.c              |   83 +++++++++++++++++++++++++++++++++
>>  arch/arm/plat-omap/include/plat/drm.h |   64 +++++++++++++++++++++++++
>>  4 files changed, 150 insertions(+), 2 deletions(-)
>>  create mode 100644 arch/arm/plat-omap/drm.c
>>  create mode 100644 arch/arm/plat-omap/include/plat/drm.h
>>
>> diff --git a/arch/arm/plat-omap/Makefile b/arch/arm/plat-omap/Makefile
>> index 9a58461..b86e6cb 100644
>> --- a/arch/arm/plat-omap/Makefile
>> +++ b/arch/arm/plat-omap/Makefile
>> @@ -4,7 +4,7 @@
>>
>>  # Common support
>>  obj-y := common.o sram.o clock.o devices.o dma.o mux.o \
>> -      usb.o fb.o counter_32k.o
>> +      usb.o fb.o counter_32k.o drm.o
>>  obj-m :=
>>  obj-n :=
>>  obj-  :=
>> diff --git a/arch/arm/plat-omap/common.c b/arch/arm/plat-omap/common.c
>> index 06383b5..0d87dab 100644
>> --- a/arch/arm/plat-omap/common.c
>> +++ b/arch/arm/plat-omap/common.c
>> @@ -21,10 +21,10 @@
>>  #include <plat/board.h>
>>  #include <plat/vram.h>
>>  #include <plat/dsp.h>
>> +#include <plat/drm.h>
>>
>>  #include <plat/omap-secure.h>
>>
>> -
>>  #define NO_LENGTH_CHECK 0xffffffff
>>
>>  struct omap_board_config_kernel *omap_board_config __initdata;
>> @@ -65,6 +65,7 @@ const void *__init omap_get_var_config(u16 tag, size_t *len)
>>
>>  void __init omap_reserve(void)
>>  {
>> +     omapdrm_reserve_vram();
>>       omapfb_reserve_sdram_memblock();
>>       omap_vram_reserve_sdram_memblock();
>>       omap_dsp_reserve_sdram_memblock();
>> diff --git a/arch/arm/plat-omap/drm.c b/arch/arm/plat-omap/drm.c
>
> As Tony said, mach-omap2 is probably a better place. fb.c is in
> plat-omap because it supports both OMAP1 and OMAP2+.
>
>> new file mode 100644
>> index 0000000..28279df
>> --- /dev/null
>> +++ b/arch/arm/plat-omap/drm.c
>> @@ -0,0 +1,83 @@
>> +/*
>> + * DRM/KMS device registration for TI OMAP platforms
>> + *
>> + * Copyright (C) 2012 Texas Instruments
>> + * Author: Rob Clark <rob.clark@linaro.org>
>> + *
>> + * 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, see <http://www.gnu.org/licenses/>.
>> + */
>> +
>> +#include <linux/module.h>
>> +#include <linux/kernel.h>
>> +#include <linux/mm.h>
>> +#include <linux/init.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/dma-mapping.h>
>> +#ifdef CONFIG_CMA
>> +#  include <linux/dma-contiguous.h>
>> +#endif
>> +
>> +#include <plat/omap_device.h>
>> +#include <plat/omap_hwmod.h>
>> +
>> +#include <plat/drm.h>
>> +
>> +#if defined(CONFIG_DRM_OMAP) || (CONFIG_DRM_OMAP_MODULE)
>> +
>> +static struct omap_drm_platform_data omapdrm_platdata;
>> +
>> +static struct platform_device omap_drm_device = {
>> +             .dev = {
>> +                     .coherent_dma_mask = DMA_BIT_MASK(32),
>> +                     .platform_data = &omapdrm_platdata,
>> +             },
>> +             .name = "omapdrm",
>> +             .id = 0,
>
> Can there be more than one omapdrm device? I guess not. If so, the id
> should be -1.

in the past, we have used multiple devices (using the platform-data to
divide up the dss resources), although this was sort of a
special-case.  But in theory you could have multiple.  (Think of a
multi-seat scenario, where multiple compositors need to run and each
need to be drm-master of their own device to do mode-setting on their
corresponding display.)

I think if we use .id = -1, then we'd end up with a funny looking
bus-id for the device: "platform:omapdrm:-1"

>> +};
>> +
>> +static int __init omap_init_gpu(void)
>> +{
>> +     struct omap_hwmod *oh = NULL;
>> +     struct platform_device *pdev;
>> +
>> +     /* lookup and populate the DMM information, if present - OMAP4+ */
>> +     oh = omap_hwmod_lookup("dmm");
>> +
>> +     if (oh) {
>> +             pdev = omap_device_build(oh->name, -1, oh, NULL, 0, NULL, 0,
>> +                                     false);
>> +             WARN(IS_ERR(pdev), "Could not build omap_device for %s\n",
>> +                     oh->name);
>> +     }
>> +
>> +     return platform_device_register(&omap_drm_device);
>> +
>> +}
>
> The function is called omap_init_gpu(), but it doesn't do anything
> related to the gpu... And aren't DMM and DRM totally separate things,
> why are they bunched together like that?

only legacy.. product branches also have sgx initialization here.  But
I can change that to omap_init_drm()

DMM is managed by the drm driver (and exposed to userspace as drm/gem
buffers, shared with other devices via dma-buf, etc).  It is only
split out to a separate device to play along with hwmod.

>> +arch_initcall(omap_init_gpu);
>> +
>> +void omapdrm_reserve_vram(void)
>> +{
>> +#ifdef CONFIG_CMA
>> +     /*
>> +      * Create private 32MiB contiguous memory area for omapdrm.0 device
>> +      * TODO revisit size.. if uc/wc buffers are allocated from CMA pages
>> +      * then the amount of memory we need goes up..
>> +      */
>> +     dma_declare_contiguous(&omap_drm_device.dev, 32 * SZ_1M, 0, 0);
>
> What does this actually do? Does it reserve the memory, i.e. it's not
> usable for others? If so, shouldn't there be a way for the user to
> configure it?

It can be re-used by others.. see http://lwn.net/Articles/479297/

BR,
-R

>> +#else
>> +#  warning "CMA is not enabled, there may be limitations about scanout buffer allocations on OMAP3 and earlier"
>> +#endif
>> +}
>> +
>> +#endif
>> diff --git a/arch/arm/plat-omap/include/plat/drm.h b/arch/arm/plat-omap/include/plat/drm.h
>> new file mode 100644
>> index 0000000..df9bc41
>> --- /dev/null
>> +++ b/arch/arm/plat-omap/include/plat/drm.h
>> @@ -0,0 +1,64 @@
>> +/*
>> + * DRM/KMS device registration for TI OMAP platforms
>> + *
>> + * Copyright (C) 2012 Texas Instruments
>> + * Author: Rob Clark <rob.clark@linaro.org>
>> + *
>> + * 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, see <http://www.gnu.org/licenses/>.
>> + */
>> +
>> +#ifndef __PLAT_OMAP_DRM_H__
>> +#define __PLAT_OMAP_DRM_H__
>> +
>> +/*
>> + * Optional platform data to configure the default configuration of which
>> + * pipes/overlays/CRTCs are used.. if this is not provided, then instead the
>> + * first CONFIG_DRM_OMAP_NUM_CRTCS are used, and they are each connected to
>> + * one manager, with priority given to managers that are connected to
>> + * detected devices.  Remaining overlays are used as video planes.  This
>> + * should be a good default behavior for most cases, but yet there still
>> + * might be times when you wish to do something different.
>> + */
>> +struct omap_kms_platform_data {
>> +     /* overlays to use as CRTCs: */
>> +     int ovl_cnt;
>> +     const int *ovl_ids;
>> +
>> +     /* overlays to use as video planes: */
>> +     int pln_cnt;
>> +     const int *pln_ids;
>> +
>> +     int mgr_cnt;
>> +     const int *mgr_ids;
>> +
>> +     int dev_cnt;
>> +     const char **dev_names;
>> +};
>> +
>> +struct omap_drm_platform_data {
>> +     struct omap_kms_platform_data *kms_pdata;
>> +};
>
> I don't know if there's need to add these... With device tree the
> plaform data will not be usable anyway.
>
>  Tomi
>
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