Hi Doug,
On Tue, Mar 23, 2021 at 12:07:27PM -0700, Doug Anderson wrote:
On Mon, Mar 22, 2021 at 8:17 PM Stephen Boyd swboyd@chromium.org wrote:
Quoting Laurent Pinchart (2021-03-17 17:20:43)
Hi Stephen,
Reviving a bit of an old thread, for a question.
On Mon, Nov 02, 2020 at 10:11:43AM -0800, Stephen Boyd wrote:
@@ -265,6 +267,23 @@ connector_to_ti_sn_bridge(struct drm_connector *connector) static int ti_sn_bridge_connector_get_modes(struct drm_connector *connector) { struct ti_sn_bridge *pdata = connector_to_ti_sn_bridge(connector);
struct edid *edid = pdata->edid;int num, ret;if (!edid) {pm_runtime_get_sync(pdata->dev);edid = pdata->edid = drm_get_edid(connector, &pdata->aux.ddc);pm_runtime_put(pdata->dev);Is there any specific reason to use the indirect access method, compared to the direct method that translates access to an I2C ancillary address to an I2C-over-AUX transaction (see page 20 of SLLSEH2B) ? The direct method seems it would be more efficient.
No I don't think it matters. I was just using the existing support code that Sean wrote instead of digging into the details. Maybe Sean ran into something earlier and abandoned that approach?
From reading the docs, it sounds as if there _could_ be a reason to use the indirect method. Specifically if the i2c host that the bridge is on doesn't support clock stretching then the direct method wouldn't work according to the docs. Is that something that we'd have to reasonably worry about?
I'm not sure. I'm going through BSP code that uses the direct method, and I was wondering if it was just an implementation detail. Once I get the display working on this board, I'll try to find time to compare the two methods, to see if there's a significatant performance improvement from the direct method. If there isn't, I won't bother.