Messages in this thread | | | Date | Fri, 14 Apr 2023 20:40:18 +0530 | Subject | Re: [PATCH v2 2/2] drm: bridge: cdns-mhdp8546: Add support for no-hpd | From | Jayesh Choudhary <> |
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On 06/04/23 07:22, Laurent Pinchart wrote: > Hi Jayesh, > > Thank you for the patch. > > On Wed, Apr 05, 2023 at 07:54:40PM +0530, Jayesh Choudhary wrote: >> From: Rahul T R <r-ravikumar@ti.com> >> >> In J721S2 EVMs DP0 hpd is not connected to correct >> hpd pin on SOC, to handle such cases, Add support for >> "no-hpd" property in the device tree node to disable >> hpd > > s/hpd/hpd./ > > You can also reflow the commit message to 72 columns.
Okay. Thanks for the suggestion. Will do.
> >> Also change the log level for dpcd read failuers to >> debug, since framework retries 32 times for each read > > s/read/read./ > > Doesn't this apply to writes as well ?
Based on message request, we went into the conditional that uses read. So just changing the log-level for dpcd read was enough to get rid of the debug logs.
> >> Signed-off-by: Rahul T R <r-ravikumar@ti.com> >> Signed-off-by: Jayesh Choudhary <j-choudhary@ti.com> >> --- >> .../drm/bridge/cadence/cdns-mhdp8546-core.c | 37 ++++++++++++++++--- >> .../drm/bridge/cadence/cdns-mhdp8546-core.h | 1 + >> 2 files changed, 33 insertions(+), 5 deletions(-) >> >> diff --git a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c >> index f6822dfa3805..e177794b069d 100644 >> --- a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c >> +++ b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c >> @@ -54,6 +54,8 @@ >> #include "cdns-mhdp8546-hdcp.h" >> #include "cdns-mhdp8546-j721e.h" >> >> +static int cdns_mhdp_update_link_status(struct cdns_mhdp_device *mhdp); >> + >> static int cdns_mhdp_mailbox_read(struct cdns_mhdp_device *mhdp) >> { >> int ret, empty; >> @@ -749,7 +751,7 @@ static int cdns_mhdp_fw_activate(const struct firmware *fw, >> * MHDP_HW_STOPPED happens only due to driver removal when >> * bridge should already be detached. >> */ >> - if (mhdp->bridge_attached) >> + if (mhdp->bridge_attached && !mhdp->no_hpd) >> writel(~(u32)CDNS_APB_INT_MASK_SW_EVENT_INT, >> mhdp->regs + CDNS_APB_INT_MASK); >> >> @@ -845,7 +847,7 @@ static ssize_t cdns_mhdp_transfer(struct drm_dp_aux *aux, >> ret = cdns_mhdp_dpcd_read(mhdp, msg->address, >> msg->buffer, msg->size); >> if (ret) { >> - dev_err(mhdp->dev, >> + dev_dbg(mhdp->dev, >> "Failed to read DPCD addr %u\n", >> msg->address); >> >> @@ -1738,6 +1740,19 @@ static int cdns_mhdp_attach(struct drm_bridge *bridge, >> >> spin_unlock(&mhdp->start_lock); >> >> + if (mhdp->no_hpd) { >> + ret = wait_event_timeout(mhdp->fw_load_wq, >> + mhdp->hw_state == MHDP_HW_READY, >> + msecs_to_jiffies(100)); >> + if (ret == 0) { >> + dev_err(mhdp->dev, "%s: Timeout waiting for fw loading\n", >> + __func__); >> + return -ETIMEDOUT; >> + } >> + >> + cdns_mhdp_update_link_status(mhdp); >> + return 0; >> + } > > Missing blank line. > > It's not clear to me while you need to wait for the state to change to > MHDP_HW_READY in the no_hpd case. This should be explained in the commit > message. > >> /* Enable SW event interrupts */ >> if (hw_ready) >> writel(~(u32)CDNS_APB_INT_MASK_SW_EVENT_INT, >> @@ -2256,7 +2271,16 @@ static int cdns_mhdp_update_link_status(struct cdns_mhdp_device *mhdp) >> >> mutex_lock(&mhdp->link_mutex); >> >> - mhdp->plugged = cdns_mhdp_detect_hpd(mhdp, &hpd_pulse); >> + if (mhdp->no_hpd) { >> + ret = drm_dp_dpcd_read_link_status(&mhdp->aux, status); >> + hpd_pulse = false; >> + if (ret < 0) >> + mhdp->plugged = false; >> + else >> + mhdp->plugged = true; > > I think there's an issue with how the driver uses mhdp->plugged. In the > no_hpd case, you try to detect if a display is connected by reading the > link status at attach time, and then never update mhdp->plugged. This > means that if no display is connected at that point, functions like > cdns_mhdp_get_edid() will always fail, even if a display gets plugged > later. As the goal of this series is (as far as I understand) support > systems where the HPD signal could be connected to a SoC GPIO instead of > the bridge, I don't think this is good enough.
In the driver, I see that this is the only call which changes mhdp->plugged. Do you have any suggestions on how to work on this? Polling the value of drm_dp_dpdc_read_link_status does not seem like a clean way. Here by doing this, we are settling for few functionalities of display.
Thanks, -Jayesh
> >> + } else { >> + mhdp->plugged = cdns_mhdp_detect_hpd(mhdp, &hpd_pulse); >> + } >> >> if (!mhdp->plugged) { >> cdns_mhdp_link_down(mhdp); >> @@ -2451,6 +2475,8 @@ static int cdns_mhdp_probe(struct platform_device *pdev) >> mhdp->aux.dev = dev; >> mhdp->aux.transfer = cdns_mhdp_transfer; >> >> + mhdp->no_hpd = of_property_read_bool(dev->of_node, "cdns,no-hpd"); >> + >> mhdp->regs = devm_platform_ioremap_resource(pdev, 0); >> if (IS_ERR(mhdp->regs)) { >> dev_err(dev, "Failed to get memory resource\n"); >> @@ -2526,8 +2552,9 @@ static int cdns_mhdp_probe(struct platform_device *pdev) >> >> mhdp->bridge.of_node = pdev->dev.of_node; >> mhdp->bridge.funcs = &cdns_mhdp_bridge_funcs; >> - mhdp->bridge.ops = DRM_BRIDGE_OP_DETECT | DRM_BRIDGE_OP_EDID | >> - DRM_BRIDGE_OP_HPD; >> + mhdp->bridge.ops = DRM_BRIDGE_OP_DETECT | DRM_BRIDGE_OP_EDID; >> + if (!mhdp->no_hpd) >> + mhdp->bridge.ops |= DRM_BRIDGE_OP_HPD; >> mhdp->bridge.type = DRM_MODE_CONNECTOR_DisplayPort; >> if (mhdp->info) >> mhdp->bridge.timings = mhdp->info->timings; >> diff --git a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.h b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.h >> index bedddd510d17..6786ccb51387 100644 >> --- a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.h >> +++ b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.h >> @@ -388,6 +388,7 @@ struct cdns_mhdp_device { >> >> bool link_up; >> bool plugged; >> + bool no_hpd; >> >> /* >> * "start_lock" protects the access to bridge_attached and >
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