Re: [PATCH 15/24] drm/i915: initialize DDI buffer translations

[Jesse Barnes <jbarnes@virtuousgeek.org>]

On Thu, 26 Apr 2012 15:21:10 -0300
Eugeni Dodonov <eugeni.dodonov@intel.com> wrote:

> DDI is introduced starting with Haswell GPU generation. So to simplify its
> management in the future, we also add intel_ddi.c to hold all the
> DDI-related items.
> 
> Buffer translations for DDI links must be initialized prior to enablement.
> For FDI and DP, first 9 pairs of values are used to select the connection
> parameters. HDMI uses the last pair of values and ignores the first 9
> pairs. So we program HDMI values in both cases, which allows HDMI to work
> over both FDI and DP-friendly buffers.
> 
> Signed-off-by: Eugeni Dodonov <eugeni.dodonov@intel.com>
> ---
>  drivers/gpu/drm/i915/Makefile        |    1 +
>  drivers/gpu/drm/i915/intel_ddi.c     |  111 ++++++++++++++++++++++++++++++++++
>  drivers/gpu/drm/i915/intel_display.c |    2 +
>  drivers/gpu/drm/i915/intel_drv.h     |    1 +
>  4 files changed, 115 insertions(+)
>  create mode 100644 drivers/gpu/drm/i915/intel_ddi.c
> 
> diff --git a/drivers/gpu/drm/i915/Makefile b/drivers/gpu/drm/i915/Makefile
> index 8b8bbc7..0ca7f76 100644
> --- a/drivers/gpu/drm/i915/Makefile
> +++ b/drivers/gpu/drm/i915/Makefile
> @@ -19,6 +19,7 @@ i915-y := i915_drv.o i915_dma.o i915_irq.o \
>  	  intel_crt.o \
>  	  intel_lvds.o \
>  	  intel_bios.o \
> +	  intel_ddi.o \
>  	  intel_dp.o \
>  	  intel_hdmi.o \
>  	  intel_sdvo.o \
> diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c
> new file mode 100644
> index 0000000..32594a8
> --- /dev/null
> +++ b/drivers/gpu/drm/i915/intel_ddi.c
> @@ -0,0 +1,111 @@
> +/*
> + * Copyright © 2012 Intel Corporation
> + *
> + * Permission is hereby granted, free of charge, to any person obtaining a
> + * copy of this software and associated documentation files (the "Software"),
> + * to deal in the Software without restriction, including without limitation
> + * the rights to use, copy, modify, merge, publish, distribute, sublicense,
> + * and/or sell copies of the Software, and to permit persons to whom the
> + * Software is furnished to do so, subject to the following conditions:
> + *
> + * The above copyright notice and this permission notice (including the next
> + * paragraph) shall be included in all copies or substantial portions of the
> + * Software.
> + *
> + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
> + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
> + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
> + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
> + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
> + * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
> + * IN THE SOFTWARE.
> + *
> + * Authors:
> + *    Eugeni Dodonov <eugeni.dodonov@intel.com>
> + *
> + */
> +
> +#include "i915_drv.h"
> +#include "intel_drv.h"
> +
> +/* HDMI/DVI modes ignore everything but the last 2 items. So we share
> + * them for both DP and FDI transports, allowing those ports to
> + * automatically adapt to HDMI connections as well
> + */
> +static const long hsw_ddi_translations_dp[] = {
> +	0x00FFFFFF, 0x0006000E,
> +	0x00D75FFF, 0x0005000A,
> +	0x00C30FFF, 0x00040006,
> +	0x80AAAFFF, 0x000B0000,
> +	0x00FFFFFF, 0x0005000A,
> +	0x00D75FFF, 0x000C0004,
> +	0x80C30FFF, 0x000B0000,
> +	0x00FFFFFF, 0x00040006,
> +	0x80D75FFF, 0x000B0000,
> +	0x00FFFFFF, 0x00040006
> +};
> +
> +static const long hsw_ddi_translations_fdi[] = {
> +	0x00FFFFFF, 0x0007000E,
> +	0x00D75FFF, 0x000F000A,
> +	0x00C30FFF, 0x00060006,
> +	0x00AAAFFF, 0x001E0000,
> +	0x00FFFFFF, 0x000F000A,
> +	0x00D75FFF, 0x00160004,
> +	0x00C30FFF, 0x001E0000,
> +	0x00FFFFFF, 0x00060006,
> +	0x00D75FFF, 0x001E0000,
> +	0x00FFFFFF, 0x00040006
> +};

Ahh these are vswing and preemphasis values for the various types...

Doesn't look like this goes up to the 19 dwords the docs specify?

> +
> +/* On Haswell, DDI port buffers must be programmed with correct values
> + * in advance. The buffer values are different for FDI and DP modes,
> + * but the HDMI/DVI fields are shared among those. So we program the DDI
> + * in either FDI or DP modes only, as HDMI connections will work with both
> + * of those
> + */
> +void intel_prepare_ddi_buffers(struct drm_device *dev, enum port port, bool use_fdi_mode)
> +{
> +	struct drm_i915_private *dev_priv = dev->dev_private;
> +	u32 reg;
> +	int i, j;
> +
> +	DRM_DEBUG_DRIVER("Initializing DDI buffers for port %c in %s mode\n",
> +			port_name(port),
> +			use_fdi_mode ? "FDI" : "DP");
> +
> +	WARN((use_fdi_mode && (port != PORT_E)),
> +		"Programming port %c in FDI mode, this probably will not work.\n",
> +		port_name(port));
> +
> +	/* Those registers seem to be double-buffered, so write them twice */
> +	for (j=0; j < 2; j++) {
> +		for (i=0, reg=DDI_BUF_TRANS(port); i < ARRAY_SIZE(hsw_ddi_translations_fdi); i++) {
> +			I915_WRITE(reg,
> +					(use_fdi_mode) ?
> +						hsw_ddi_translations_fdi[i] :
> +						hsw_ddi_translations_dp[i]);
> +			reg += 4;
> +		}
> +		udelay(20);
> +	}

Usually, double buffered means we need to write a trigger reg somewhere
for the values to be latched in, or wait for vblank.  What's different
here?

-- 
Jesse Barnes, Intel Open Source Technology Center
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