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Message-ID: <2a7c2edc-b83c-dccf-487d-1415b4bc23ff@xs4all.nl>
Date: Thu, 4 Feb 2021 11:19:34 +0100
From: Hans Verkuil <hverkuil@...all.nl>
To: Ville Syrjälä <ville.syrjala@...ux.intel.com>,
Sam McNally <sammc@...omium.org>
Cc: LKML <linux-kernel@...r.kernel.org>,
Thomas Zimmermann <tzimmermann@...e.de>,
David Airlie <airlied@...ux.ie>,
Hans Verkuil <hans.verkuil@...co.com>,
dri-devel@...ts.freedesktop.org
Subject: Re: [PATCH v3 2/4] drm_dp_mst_topology: use correct AUX channel
On 01/02/2021 23:13, Ville Syrjälä wrote:
> On Wed, Sep 23, 2020 at 12:13:53PM +1000, Sam McNally wrote:
>> From: Hans Verkuil <hans.verkuil@...co.com>
>>
>> For adapters behind an MST hub use the correct AUX channel.
>>
>> Signed-off-by: Hans Verkuil <hans.verkuil@...co.com>
>> [sammc@...omium.org: rebased, removing redundant changes]
>> Signed-off-by: Sam McNally <sammc@...omium.org>
>> ---
>>
>> (no changes since v1)
>>
>> drivers/gpu/drm/drm_dp_mst_topology.c | 36 +++++++++++++++++++++++++++
>> 1 file changed, 36 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
>> index 15b6cc39a754..0d753201adbd 100644
>> --- a/drivers/gpu/drm/drm_dp_mst_topology.c
>> +++ b/drivers/gpu/drm/drm_dp_mst_topology.c
>> @@ -2255,6 +2255,9 @@ drm_dp_mst_topology_unlink_port(struct drm_dp_mst_topology_mgr *mgr,
>> drm_dp_mst_topology_put_port(port);
>> }
>>
>> +static ssize_t
>> +drm_dp_mst_aux_transfer(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg);
>> +
>> static struct drm_dp_mst_port *
>> drm_dp_mst_add_port(struct drm_device *dev,
>> struct drm_dp_mst_topology_mgr *mgr,
>> @@ -2271,9 +2274,13 @@ drm_dp_mst_add_port(struct drm_device *dev,
>> port->port_num = port_number;
>> port->mgr = mgr;
>> port->aux.name = "DPMST";
>> + mutex_init(&port->aux.hw_mutex);
>> + mutex_init(&port->aux.cec.lock);
>> port->aux.dev = dev->dev;
>> port->aux.is_remote = true;
>>
>> + port->aux.transfer = drm_dp_mst_aux_transfer;
>> +
>
> This was supposed to be handled via higher levels checking for
> is_remote==true.
Ah, I suspect this patch can be dropped entirely: it predates commit 2f221a5efed4
("drm/dp_mst: Add MST support to DP DPCD R/W functions").
It looks like that commit basically solved what this older patch attempts to do
as well.
Sam, can you test if it works without this patch?
Regards,
Hans
>
>> /* initialize the MST downstream port's AUX crc work queue */
>> drm_dp_remote_aux_init(&port->aux);
>>
>> @@ -3503,6 +3510,35 @@ static int drm_dp_send_up_ack_reply(struct drm_dp_mst_topology_mgr *mgr,
>> return 0;
>> }
>>
>> +static ssize_t
>> +drm_dp_mst_aux_transfer(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg)
>> +{
>> + struct drm_dp_mst_port *port =
>> + container_of(aux, struct drm_dp_mst_port, aux);
>> + int ret;
>> +
>> + switch (msg->request & ~DP_AUX_I2C_MOT) {
>> + case DP_AUX_NATIVE_WRITE:
>> + case DP_AUX_I2C_WRITE:
>> + case DP_AUX_I2C_WRITE_STATUS_UPDATE:
>> + ret = drm_dp_send_dpcd_write(port->mgr, port, msg->address,
>> + msg->size, msg->buffer);
>
> That doesn't make sense to me. I2c writes and DPCD writes
> are definitely not the same thing.
>
> aux->transfer is a very low level thing. I don't think it's the
> correct level of abstraction for sideband.
>
>> + break;
>> +
>> + case DP_AUX_NATIVE_READ:
>> + case DP_AUX_I2C_READ:
>> + ret = drm_dp_send_dpcd_read(port->mgr, port, msg->address,
>> + msg->size, msg->buffer);
>> + break;
>> +
>> + default:
>> + ret = -EINVAL;
>> + break;
>> + }
>> +
>> + return ret;
>> +}
>> +
>> static int drm_dp_get_vc_payload_bw(u8 dp_link_bw, u8 dp_link_count)
>> {
>> if (dp_link_bw == 0 || dp_link_count == 0)
>> --
>> 2.28.0.681.g6f77f65b4e-goog
>>
>> _______________________________________________
>> dri-devel mailing list
>> dri-devel@...ts.freedesktop.org
>> https://lists.freedesktop.org/mailman/listinfo/dri-devel
>
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