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Message-ID: <20171205170203.mlgwznpot2ap5na2@phenom.ffwll.local>
Date: Tue, 5 Dec 2017 18:02:03 +0100
From: Daniel Vetter <daniel@...ll.ch>
To: Sean Paul <seanpaul@...omium.org>
Cc: dri-devel@...ts.freedesktop.org, intel-gfx@...ts.freedesktop.org,
seanpaul@...gle.com, David Airlie <airlied@...ux.ie>,
linux-kernel@...r.kernel.org,
Rodrigo Vivi <rodrigo.vivi@...el.com>, daniel.vetter@...el.com
Subject: Re: [Intel-gfx] [PATCH v3 7/9] drm/i915: Add function to output Aksv
over GMBUS
On Tue, Dec 05, 2017 at 12:15:06AM -0500, Sean Paul wrote:
> Once the Aksv is available in the PCH, we need to get it on the wire to
> the receiver via DDC. The hardware doesn't allow us to read the value
> directly, so we need to tell GMBUS to source the Aksv internally and
> send it to the right offset on the receiver.
>
> The way we do this is to initiate an indexed write where the index is
> the Aksv register offset. We write dummy values to GMBUS3 as if we were
> sending the key, and the hardware slips in the "real" values when it
> goes out.
>
> Changes in v2:
> - None
> Changes in v3:
> - Uses new index write feature (Ville)
>
> Cc: Ville Syrjälä <ville.syrjala@...ux.intel.com>
> Signed-off-by: Sean Paul <seanpaul@...omium.org>
Reviewed-by: Daniel Vetter <daniel.vetter@...ll.ch>
> ---
> drivers/gpu/drm/i915/i915_drv.h | 1 +
> drivers/gpu/drm/i915/i915_reg.h | 1 +
> drivers/gpu/drm/i915/intel_i2c.c | 47 +++++++++++++++++++++++++++++++++++++---
> 3 files changed, 46 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index bddd65839f60..6b39081c5e53 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -4049,6 +4049,7 @@ extern int intel_setup_gmbus(struct drm_i915_private *dev_priv);
> extern void intel_teardown_gmbus(struct drm_i915_private *dev_priv);
> extern bool intel_gmbus_is_valid_pin(struct drm_i915_private *dev_priv,
> unsigned int pin);
> +extern int intel_gmbus_output_aksv(struct i2c_adapter *adapter);
>
> extern struct i2c_adapter *
> intel_gmbus_get_adapter(struct drm_i915_private *dev_priv, unsigned int pin);
> diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> index 2bd2cc8441d4..107e16392710 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -3043,6 +3043,7 @@ enum i915_power_well_id {
> # define GPIO_DATA_PULLUP_DISABLE (1 << 13)
>
> #define GMBUS0 _MMIO(dev_priv->gpio_mmio_base + 0x5100) /* clock/port select */
> +#define GMBUS_AKSV_SELECT (1<<11)
> #define GMBUS_RATE_100KHZ (0<<8)
> #define GMBUS_RATE_50KHZ (1<<8)
> #define GMBUS_RATE_400KHZ (2<<8) /* reserved on Pineview */
> diff --git a/drivers/gpu/drm/i915/intel_i2c.c b/drivers/gpu/drm/i915/intel_i2c.c
> index 7399009aee0a..0a4c7486fc7b 100644
> --- a/drivers/gpu/drm/i915/intel_i2c.c
> +++ b/drivers/gpu/drm/i915/intel_i2c.c
> @@ -30,6 +30,7 @@
> #include <linux/i2c-algo-bit.h>
> #include <linux/export.h>
> #include <drm/drmP.h>
> +#include <drm/drm_hdcp.h>
> #include "intel_drv.h"
> #include <drm/i915_drm.h>
> #include "i915_drv.h"
> @@ -497,7 +498,8 @@ gmbus_xfer_index_read(struct drm_i915_private *dev_priv, struct i2c_msg *msgs)
> }
>
> static int
> -do_gmbus_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs, int num)
> +do_gmbus_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs, int num,
> + u32 gmbus0_source)
> {
> struct intel_gmbus *bus = container_of(adapter,
> struct intel_gmbus,
> @@ -507,7 +509,7 @@ do_gmbus_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs, int num)
> int ret = 0;
>
> retry:
> - I915_WRITE_FW(GMBUS0, bus->reg0);
> + I915_WRITE_FW(GMBUS0, gmbus0_source | bus->reg0);
>
> for (; i < num; i += inc) {
> inc = 1;
> @@ -629,7 +631,7 @@ gmbus_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs, int num)
> if (ret < 0)
> bus->force_bit &= ~GMBUS_FORCE_BIT_RETRY;
> } else {
> - ret = do_gmbus_xfer(adapter, msgs, num);
> + ret = do_gmbus_xfer(adapter, msgs, num, 0);
> if (ret == -EAGAIN)
> bus->force_bit |= GMBUS_FORCE_BIT_RETRY;
> }
> @@ -639,6 +641,45 @@ gmbus_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs, int num)
> return ret;
> }
>
> +int intel_gmbus_output_aksv(struct i2c_adapter *adapter)
> +{
> + struct intel_gmbus *bus = container_of(adapter, struct intel_gmbus,
> + adapter);
> + struct drm_i915_private *dev_priv = bus->dev_priv;
> + int ret;
> + u8 cmd = DRM_HDCP_DDC_AKSV ;
> + u8 buf[DRM_HDCP_KSV_LEN] = { 0 };
> + struct i2c_msg msgs[] = {
> + {
> + .addr = DRM_HDCP_DDC_ADDR,
> + .flags = 0,
> + .len = sizeof(cmd),
> + .buf = &cmd,
> + },
> + {
> + .addr = DRM_HDCP_DDC_ADDR,
> + .flags = 0,
> + .len = sizeof(buf),
> + .buf = buf,
> + }
> + };
> +
> + intel_display_power_get(dev_priv, POWER_DOMAIN_GMBUS);
> + mutex_lock(&dev_priv->gmbus_mutex);
> +
> + /*
> + * In order to output Aksv to the receiver, use an indexed write to
> + * pass the i2c command, and tell GMBUS to use the HW-provided value
> + * instead of sourcing GMBUS3 for the data.
> + */
> + ret = do_gmbus_xfer(adapter, msgs, ARRAY_SIZE(msgs), GMBUS_AKSV_SELECT);
> +
> + mutex_unlock(&dev_priv->gmbus_mutex);
> + intel_display_power_put(dev_priv, POWER_DOMAIN_GMBUS);
> +
> + return ret;
> +}
> +
> static u32 gmbus_func(struct i2c_adapter *adapter)
> {
> return i2c_bit_algo.functionality(adapter) &
> --
> 2.15.0.531.g2ccb3012c9-goog
>
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx@...ts.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/intel-gfx
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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