Re: [PATCH 5/5] drm/bridge: dw-mipi-dsi: Fix dsi registration during drm probing

Hi Sam

On Sat, Oct 16, 2021 at 2:25 PM Sam Ravnborg sam@ravnborg.org wrote:

Hi Michael,

I fail to follow the logic in this patch.

On Sat, Oct 16, 2021 at 10:22:32AM +0000, Michael Trimarchi wrote:

...

The dsi registration is implemented in rockchip platform driver. The attach can be called before the probe is terminated and therefore we need to be sure that corresponding entry during attach is valid

Signed-off-by: Michael Trimarchi michael@amarulasolutions.com

drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c | 8 +++++++- drivers/gpu/drm/rockchip/dw-mipi-dsi-rockchip.c | 12 ++++++++---- include/drm/bridge/dw_mipi_dsi.h | 2 +- 3 files changed, 16 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c b/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c index e44e18a0112a..44b211be15fc 100644 --- a/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c +++ b/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c @@ -362,8 +362,14 @@ static int dw_mipi_dsi_host_attach(struct mipi_dsi_host *host, dsi->device_found = true; }

• /*
  

•  * NOTE: the dsi registration is implemented in
  

•  * platform driver, that to say dsi would be exist after
  

•  * probe is terminated. The call is done before the end of probe
  

•  * so we need to pass the dsi to the platform driver.
  

•  */
  if (pdata->host_ops && pdata->host_ops->attach) {
  

•         ret = pdata->host_ops->attach(pdata->priv_data, device);
  

•         ret = pdata->host_ops->attach(pdata->priv_data, device, dsi);
          if (ret < 0)
                  return ret;
  }
  

diff --git a/drivers/gpu/drm/rockchip/dw-mipi-dsi-rockchip.c b/drivers/gpu/drm/rockchip/dw-mipi-dsi-rockchip.c index a2262bee5aa4..32ddc8642ec1 100644 --- a/drivers/gpu/drm/rockchip/dw-mipi-dsi-rockchip.c +++ b/drivers/gpu/drm/rockchip/dw-mipi-dsi-rockchip.c @@ -997,7 +997,8 @@ static const struct component_ops dw_mipi_dsi_rockchip_ops = { };

static int dw_mipi_dsi_rockchip_host_attach(void *priv_data,

•                                     struct mipi_dsi_device *device)
  

•                                     struct mipi_dsi_device *device,
  

•                                     struct dw_mipi_dsi *dmd)
  

{ struct dw_mipi_dsi_rockchip *dsi = priv_data; struct device *second; @@ -1005,6 +1006,8 @@ static int dw_mipi_dsi_rockchip_host_attach(void *priv_data,

  mutex_lock(&dsi->usage_mutex);

• dsi->dmd = dmd;
  

• if (dsi->usage_mode != DW_DSI_USAGE_IDLE) {
          DRM_DEV_ERROR(dsi->dev, "dsi controller already in use\n");
          mutex_unlock(&dsi->usage_mutex);
  

@@ -1280,6 +1283,7 @@ static int dw_mipi_dsi_rockchip_probe(struct platform_device *pdev) { struct device *dev = &pdev->dev; struct device_node *np = dev->of_node;

• struct dw_mipi_dsi *dmd;
  struct dw_mipi_dsi_rockchip *dsi;
  struct phy_provider *phy_provider;
  struct resource *res;
  

@@ -1391,9 +1395,9 @@ static int dw_mipi_dsi_rockchip_probe(struct platform_device *pdev) if (IS_ERR(phy_provider)) return PTR_ERR(phy_provider);

• dsi->dmd = dw_mipi_dsi_probe(pdev, &dsi->pdata);
  

• if (IS_ERR(dsi->dmd)) {
  

•         ret = PTR_ERR(dsi->dmd);
  

• dmd = dw_mipi_dsi_probe(pdev, &dsi->pdata);
  

• if (IS_ERR(dmd)) {
  

•         ret = PTR_ERR(dmd);
  

The memory pointed to by dmd is allocated in dw_mipi_dsi_probe(), but the pointer is not saved here. We rely on the attach operation to save the dmd pointer.

In other words - the attach operation must be called before we call dw_mipi_dsi_rockchip_remove(), which uses the dmd member.

This all looks wrong to me - are we papering over some other issue

Ok, it's wrong. I was not expecting that call.Anyway this was my path on linux-next

dw_mipi_dsi_rockchip_probe dw_mipi_dsi_probe -->start call

dw_mipi_dsi_rockchip_host_attach <-- this was not able to use dmd

dw_mipi_dsi_probe -> exit from the call

Michael

here?

    Sam