[RFC PATCH 6/7] drm: add support for DisplayPort CEC-Tunneling-over-AUX
Clint Taylor
clinton.a.taylor at intel.com
Tue May 30 23:57:01 UTC 2017
On 05/26/2017 12:18 AM, Daniel Vetter wrote:
> On Thu, May 25, 2017 at 05:06:25PM +0200, Hans Verkuil wrote:
>> From: Hans Verkuil <hans.verkuil at cisco.com>
>>
>> This adds support for the DisplayPort CEC-Tunneling-over-AUX
>> feature that is part of the DisplayPort 1.3 standard.
>>
>> Unfortunately, not all DisplayPort/USB-C to HDMI adapters with a
>> chip that has this capability actually hook up the CEC pin, so
>> even though a CEC device is created, it may not actually work.
>>
>> Signed-off-by: Hans Verkuil <hans.verkuil at cisco.com>
>> ---
>> drivers/gpu/drm/Kconfig | 3 +
>> drivers/gpu/drm/Makefile | 1 +
>> drivers/gpu/drm/drm_dp_cec.c | 196 +++++++++++++++++++++++++++++++++++++++++++
>> include/drm/drm_dp_helper.h | 24 ++++++
>> 4 files changed, 224 insertions(+)
>> create mode 100644 drivers/gpu/drm/drm_dp_cec.c
>>
>> diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
>> index 78d7fc0ebb57..dd771ce8a3d0 100644
>> --- a/drivers/gpu/drm/Kconfig
>> +++ b/drivers/gpu/drm/Kconfig
>> @@ -120,6 +120,9 @@ config DRM_LOAD_EDID_FIRMWARE
>> default case is N. Details and instructions how to build your own
>> EDID data are given in Documentation/EDID/HOWTO.txt.
>>
>> +config DRM_DP_CEC
>> + bool
> We generally don't bother with a Kconfig for every little bit in drm, not
> worth the trouble (yes I know there's some exceptions, but somehow they're
> all from soc people). Just smash this into the KMS_HELPER one and live is
> much easier for drivers. Also allows you to drop the dummy inline
> functions.
All of the functions like cec_register_adapter() require
CONFIG_MEDIA_CEC_SUPPORT.
This will add a new dependency to the DRM drivers. All instances of
CONFIG_DRM_DP_CEC should be changed to CONFIG_MEDIA_CEC_SUPPORT so drm
can still be used without the media CEC drivers.
-Clint
> The other nitpick: Pls kernel-doc the functions exported to drivers, and
> then pull them into Documentation/gpu/drm-kms-helpers.rst, next to the
> existing DP helper section.
>
> Thanks, Daniel
>
>> +
>> config DRM_TTM
>> tristate
>> depends on DRM && MMU
>> diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile
>> index 59f0f9b696eb..22f1a17dfc8a 100644
>> --- a/drivers/gpu/drm/Makefile
>> +++ b/drivers/gpu/drm/Makefile
>> @@ -34,6 +34,7 @@ drm_kms_helper-y := drm_crtc_helper.o drm_dp_helper.o drm_probe_helper.o \
>> drm_simple_kms_helper.o drm_modeset_helper.o \
>> drm_scdc_helper.o
>>
>> +drm_kms_helper-$(CONFIG_DRM_DP_CEC) += drm_dp_cec.o
>> drm_kms_helper-$(CONFIG_DRM_LOAD_EDID_FIRMWARE) += drm_edid_load.o
>> drm_kms_helper-$(CONFIG_DRM_FBDEV_EMULATION) += drm_fb_helper.o
>> drm_kms_helper-$(CONFIG_DRM_KMS_CMA_HELPER) += drm_fb_cma_helper.o
>> diff --git a/drivers/gpu/drm/drm_dp_cec.c b/drivers/gpu/drm/drm_dp_cec.c
>> new file mode 100644
>> index 000000000000..44c544ba53cb
>> --- /dev/null
>> +++ b/drivers/gpu/drm/drm_dp_cec.c
>> @@ -0,0 +1,196 @@
>> +/*
>> + * DisplayPort CEC-Tunneling-over-AUX support
>> + *
>> + * Copyright 2017 Cisco Systems, Inc. and/or its affiliates. All rights reserved.
>> + *
>> + * This program is free software; you may redistribute it and/or modify
>> + * it under the terms of the GNU General Public License as published by
>> + * the Free Software Foundation; version 2 of the License.
>> + *
>> + * 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.
>> + */
>> +
>> +#include <linux/kernel.h>
>> +#include <linux/module.h>
>> +#include <linux/slab.h>
>> +#include <drm/drm_dp_helper.h>
>> +#include <media/cec.h>
>> +
>> +static int drm_dp_cec_adap_enable(struct cec_adapter *adap, bool enable)
>> +{
>> + struct drm_dp_aux *aux = cec_get_drvdata(adap);
>> + ssize_t err = 0;
>> +
>> + if (enable)
>> + err = drm_dp_dpcd_writeb(aux, DP_CEC_TUNNELING_CONTROL,
>> + DP_CEC_TUNNELING_ENABLE);
>> + else
>> + err = drm_dp_dpcd_writeb(aux, DP_CEC_TUNNELING_CONTROL, 0);
>> + return (enable && err < 0) ? err : 0;
>> +}
>> +
>> +static int drm_dp_cec_adap_log_addr(struct cec_adapter *adap, u8 addr)
>> +{
>> + struct drm_dp_aux *aux = cec_get_drvdata(adap);
>> + u8 mask[2] = { 0x00, 0x80 };
>> + ssize_t err;
>> +
>> + if (addr != CEC_LOG_ADDR_INVALID) {
>> + u16 la_mask = adap->log_addrs.log_addr_mask;
>> +
>> + la_mask |= 0x8000 | (1 << addr);
>> + mask[0] = la_mask & 0xff;
>> + mask[1] = la_mask >> 8;
>> + }
>> + err = drm_dp_dpcd_write(aux, DP_CEC_LOGICAL_ADDRESS_MASK, mask, 2);
>> + return (addr != CEC_LOG_ADDR_INVALID && err < 0) ? err : 0;
>> +}
>> +
>> +static int drm_dp_cec_adap_transmit(struct cec_adapter *adap, u8 attempts,
>> + u32 signal_free_time, struct cec_msg *msg)
>> +{
>> + struct drm_dp_aux *aux = cec_get_drvdata(adap);
>> + unsigned int retries = attempts - 1;
>> + ssize_t err;
>> +
>> + err = drm_dp_dpcd_write(aux, DP_CEC_TX_MESSAGE_BUFFER,
>> + msg->msg, msg->len);
>> + if (err < 0)
>> + return err;
>> +
>> + if (retries > 5)
>> + retries = 5;
>> + err = drm_dp_dpcd_writeb(aux, DP_CEC_TX_MESSAGE_INFO,
>> + (msg->len - 1) | (retries << 4) |
>> + DP_CEC_TX_MESSAGE_SEND);
>> + return err < 0 ? err : 0;
>> +}
>> +
>> +static int drm_dp_cec_adap_monitor_all_enable(struct cec_adapter *adap,
>> + bool enable)
>> +{
>> + struct drm_dp_aux *aux = cec_get_drvdata(adap);
>> + ssize_t err;
>> + u8 val;
>> +
>> + if (!(adap->capabilities & CEC_CAP_MONITOR_ALL))
>> + return 0;
>> +
>> + err = drm_dp_dpcd_readb(aux, DP_CEC_TUNNELING_CONTROL, &val);
>> + if (err >= 0) {
>> + if (enable)
>> + val |= DP_CEC_SNOOPING_ENABLE;
>> + else
>> + val &= ~DP_CEC_SNOOPING_ENABLE;
>> + err = drm_dp_dpcd_writeb(aux, DP_CEC_TUNNELING_CONTROL, val);
>> + }
>> + return (enable && err < 0) ? err : 0;
>> +}
>> +
>> +static const struct cec_adap_ops drm_dp_cec_adap_ops = {
>> + .adap_enable = drm_dp_cec_adap_enable,
>> + .adap_log_addr = drm_dp_cec_adap_log_addr,
>> + .adap_transmit = drm_dp_cec_adap_transmit,
>> + .adap_monitor_all_enable = drm_dp_cec_adap_monitor_all_enable,
>> +};
>> +
>> +static int drm_dp_cec_received(struct drm_dp_aux *aux)
>> +{
>> + struct cec_adapter *adap = aux->cec_adap;
>> + struct cec_msg msg;
>> + u8 rx_msg_info;
>> + ssize_t err;
>> +
>> + err = drm_dp_dpcd_readb(aux, DP_CEC_RX_MESSAGE_INFO, &rx_msg_info);
>> + if (err < 0)
>> + return err;
>> + if (!(rx_msg_info & DP_CEC_RX_MESSAGE_ENDED))
>> + return 0;
>> + msg.len = (rx_msg_info & DP_CEC_RX_MESSAGE_LEN_MASK) + 1;
>> + err = drm_dp_dpcd_read(aux, DP_CEC_RX_MESSAGE_BUFFER, msg.msg, msg.len);
>> + if (err < 0)
>> + return err;
>> + cec_received_msg(adap, &msg);
>> + return 0;
>> +}
>> +
>> +int drm_dp_cec_irq(struct drm_dp_aux *aux)
>> +{
>> + struct cec_adapter *adap = aux->cec_adap;
>> + u8 flags;
>> + ssize_t err;
>> +
>> + if (!aux->cec_adap)
>> + return 0;
>> +
>> + err = drm_dp_dpcd_readb(aux, DP_CEC_TUNNELING_IRQ_FLAGS, &flags);
>> + if (err < 0)
>> + return err;
>> +
>> + if (flags & DP_CEC_RX_MESSAGE_INFO_VALID)
>> + drm_dp_cec_received(aux);
>> +
>> + if (flags & DP_CEC_TX_MESSAGE_SENT)
>> + cec_transmit_done(adap, CEC_TX_STATUS_OK, 0, 0, 0, 0);
>> + else if (flags & DP_CEC_TX_LINE_ERROR)
>> + cec_transmit_done(adap, CEC_TX_STATUS_ERROR |
>> + CEC_TX_STATUS_MAX_RETRIES, 0, 0, 0, 1);
>> + else if (flags &
>> + (DP_CEC_TX_ADDRESS_NACK_ERROR | DP_CEC_TX_DATA_NACK_ERROR))
>> + cec_transmit_done(adap, CEC_TX_STATUS_NACK |
>> + CEC_TX_STATUS_MAX_RETRIES, 0, 1, 0, 0);
>> + drm_dp_dpcd_writeb(aux, DP_CEC_TUNNELING_IRQ_FLAGS, flags);
>> + return 0;
>> +}
>> +EXPORT_SYMBOL(drm_dp_cec_irq);
>> +
>> +int drm_dp_cec_configure_adapter(struct drm_dp_aux *aux, const char *name,
>> + struct device *parent)
>> +{
>> + u32 cec_caps = CEC_CAP_LOG_ADDRS | CEC_CAP_TRANSMIT |
>> + CEC_CAP_PASSTHROUGH | CEC_CAP_RC | CEC_CAP_NEEDS_HPD;
>> + unsigned int num_las = 1;
>> + int err;
>> + u8 cap;
>> +
>> + if (drm_dp_dpcd_readb(aux, DP_CEC_TUNNELING_CAPABILITY, &cap) != 1 ||
>> + !(cap & DP_CEC_TUNNELING_CAPABLE)) {
>> + cec_unregister_adapter(aux->cec_adap);
>> + aux->cec_adap = NULL;
>> + return -ENODEV;
>> + }
>> +
>> + if (cap & DP_CEC_SNOOPING_CAPABLE)
>> + cec_caps |= CEC_CAP_MONITOR_ALL;
>> + if (cap & DP_CEC_MULTIPLE_LA_CAPABLE)
>> + num_las = CEC_MAX_LOG_ADDRS;
>> +
>> + if (!IS_ERR_OR_NULL(aux->cec_adap)) {
>> + if (aux->cec_adap->capabilities == cec_caps &&
>> + aux->cec_adap->available_log_addrs == num_las)
>> + return 0;
>> + cec_unregister_adapter(aux->cec_adap);
>> + }
>> +
>> + aux->cec_adap = cec_allocate_adapter(&drm_dp_cec_adap_ops,
>> + aux, name, cec_caps, num_las);
>> + if (IS_ERR(aux->cec_adap)) {
>> + err = PTR_ERR(aux->cec_adap);
>> + aux->cec_adap = NULL;
>> + return err;
>> + }
>> + err = cec_register_adapter(aux->cec_adap, parent);
>> + if (err) {
>> + cec_delete_adapter(aux->cec_adap);
>> + aux->cec_adap = NULL;
>> + }
>> + return err;
>> +}
>> +EXPORT_SYMBOL(drm_dp_cec_configure_adapter);
>> diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h
>> index 3f4ad709534e..1e373df48108 100644
>> --- a/include/drm/drm_dp_helper.h
>> +++ b/include/drm/drm_dp_helper.h
>> @@ -843,6 +843,8 @@ struct drm_dp_aux_msg {
>> size_t size;
>> };
>>
>> +struct cec_adapter;
>> +
>> /**
>> * struct drm_dp_aux - DisplayPort AUX channel
>> * @name: user-visible name of this AUX channel and the I2C-over-AUX adapter
>> @@ -901,6 +903,10 @@ struct drm_dp_aux {
>> * @i2c_defer_count: Counts I2C DEFERs, used for DP validation.
>> */
>> unsigned i2c_defer_count;
>> + /**
>> + * @cec_adap: the CEC adapter for CEC-Tunneling-over-AUX support.
>> + */
>> + struct cec_adapter *cec_adap;
>> };
>>
>> ssize_t drm_dp_dpcd_read(struct drm_dp_aux *aux, unsigned int offset,
>> @@ -972,4 +978,22 @@ void drm_dp_aux_unregister(struct drm_dp_aux *aux);
>> int drm_dp_start_crc(struct drm_dp_aux *aux, struct drm_crtc *crtc);
>> int drm_dp_stop_crc(struct drm_dp_aux *aux);
>>
>> +#ifdef CONFIG_DRM_DP_CEC
>> +int drm_dp_cec_irq(struct drm_dp_aux *aux);
>> +int drm_dp_cec_configure_adapter(struct drm_dp_aux *aux, const char *name,
>> + struct device *parent);
>> +#else
>> +static inline int drm_dp_cec_irq(struct drm_dp_aux *aux)
>> +{
>> + return 0;
>> +}
>> +
>> +static inline int drm_dp_cec_configure_adapter(struct drm_dp_aux *aux,
>> + const char *name,
>> + struct device *parent)
>> +{
>> + return -ENODEV;
>> +}
>> +#endif
>> +
>> #endif /* _DRM_DP_HELPER_H_ */
>> --
>> 2.11.0
>>
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