On Wed, Feb 23, 2022 at 11:14:12PM +0800, Sui Jingfeng wrote:
>
> On 2022/2/23 22:39, Maxime Ripard wrote:
> > On Tue, Feb 22, 2022 at 10:46:35PM +0800, Sui Jingfeng wrote:
> > > On 2022/2/22 16:27, Maxime Ripard wrote:
> > > > > + if (!of_device_is_available(output)) {
> > > > > + of_node_put(output);
> > > > > + drm_info(ddev, "connector%d is not available\n", index);
> > > > > + return NULL;
> > > > > + }
> > > > > +
> > > > > + disp_tims_np = of_get_child_by_name(output, "display-timings");
> > > > > + if (disp_tims_np) {
> > > > > + lsdc_get_display_timings_from_dtb(output, &lconn->disp_tim);
> > > > > + lconn->has_disp_tim = true;
> > > > > + of_node_put(disp_tims_np);
> > > > > + drm_info(ddev, "Found display timings provided by connector%d\n", index);
> > > > > + }
> > > > > +
> > > > > + connector_type = lsdc_get_connector_type(ddev, output, index);
> > > > > +
> > > > > + if (output) {
> > > > > + of_node_put(output);
> > > > > + output = NULL;
> > > > > + }
> > > > > +
> > > > > +DT_SKIPED:
> > > > > +
> > > > > + /* Only create the i2c channel if display timing is not provided */
> > > > > + if (!lconn->has_disp_tim) {
> > > > > + const struct lsdc_chip_desc * const desc = ldev->desc;
> > > > > +
> > > > > + if (desc->have_builtin_i2c)
> > > > > + lconn->ddc = lsdc_create_i2c_chan(ddev, index);
> > > > > + else
> > > > > + lconn->ddc = lsdc_get_i2c_adapter(ddev, index);
> > > > This looks weird: the connector bindings have a property to store the
> > > > i2c controller connected to the DDC lines, so you should use that
> > > > instead.
> > > >
> > > This is not weird, ast, mgag200, hibmc do the same thing.
> > And none of them have DT support.
> >
> > Maxime
>
> You are wrong, ast driver have dt support. See ast_detect_config_mode() in
> drm/ast/ast_main.c
>
> static void ast_detect_config_mode(struct drm_device *dev, u32 *scu_rev)
> {
> struct device_node *np = dev->dev->of_node;
> struct ast_private *ast = to_ast_private(dev);
> struct pci_dev *pdev = to_pci_dev(dev->dev);
> uint32_t data, jregd0, jregd1;
>
> /* Defaults */
> ast->config_mode = ast_use_defaults;
> *scu_rev = 0xffffffff;
>
> /* Check if we have device-tree properties */
> if (np && !of_property_read_u32(np, "aspeed,scu-revision-id",
> scu_rev)) {
> /* We do, disable P2A access */
> ast->config_mode = ast_use_dt;
> drm_info(dev, "Using device-tree for configuration\n");
> return;
> }
>
> ....
>
> }
It doesn't seem to probe from the DT though. It uses 4 properties, and
none of them are documented. It's still a widely different case than
your driver that uses the connector binding, and therefore has access to
the ddc bus there.
Maxime
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