Hi,
On 19/07/2022 11:08, Aradhya Bhatia wrote:
The AM625 DSS peripheral supports 2 OLDI TXes which can work to enable 2
duplicated displays of smaller resolutions or enable a single Dual-Link
display with a higher resolution (1920x1200).
Configure the necessary register to enable the different modes.
Signed-off-by: Aradhya Bhatia <a-bhatia1@xxxxxx>
---
drivers/gpu/drm/tidss/tidss_dispc.c | 44 +++++++++++++++++++++++++++--
1 file changed, 41 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/tidss/tidss_dispc.c b/drivers/gpu/drm/tidss/tidss_dispc.c
index 0b9689453ee8..28cb61259471 100644
--- a/drivers/gpu/drm/tidss/tidss_dispc.c
+++ b/drivers/gpu/drm/tidss/tidss_dispc.c
@@ -1021,8 +1021,8 @@ static void dispc_enable_oldi(struct dispc_device *dispc, u32 hw_videoport,
int count = 0;
/*
- * For the moment DUALMODESYNC, MASTERSLAVE, MODE, and SRC
- * bits of DISPC_VP_DSS_OLDI_CFG are set statically to 0.
+ * For the moment MASTERSLAVE, and SRC bits of DISPC_VP_DSS_OLDI_CFG are
+ * set statically to 0.
*/
if (fmt->data_width == 24)
@@ -1039,7 +1039,45 @@ static void dispc_enable_oldi(struct dispc_device *dispc, u32 hw_videoport,
oldi_cfg |= BIT(0); /* ENABLE */
- dispc_vp_write(dispc, hw_videoport, DISPC_VP_DSS_OLDI_CFG, oldi_cfg);
+ /*
+ * As per all the current implementations of DSS, the OLDI TXes are present only on
+ * hw_videoport = 0 (OLDI TX 0). However, the config register for 2nd OLDI TX (OLDI TX 1)
+ * is present in the address space of hw_videoport = 1. Hence, using "hw_videoport + 1" to
+ * configure OLDI TX 1.
+ */
+
+ switch (dispc->oldi_mode) {
+ case OLDI_MODE_OFF:
+ oldi_cfg &= ~BIT(0); /* DISABLE */
+ dispc_vp_write(dispc, hw_videoport, DISPC_VP_DSS_OLDI_CFG, oldi_cfg);
+ dispc_vp_write(dispc, hw_videoport + 1, DISPC_VP_DSS_OLDI_CFG, oldi_cfg);
+ break;
+
+ case OLDI_SINGLE_LINK_SINGLE_MODE_0:
+ dispc_vp_write(dispc, hw_videoport, DISPC_VP_DSS_OLDI_CFG, oldi_cfg);
+ break;
+
+ case OLDI_SINGLE_LINK_SINGLE_MODE_1:
+ dispc_vp_write(dispc, hw_videoport + 1, DISPC_VP_DSS_OLDI_CFG, oldi_cfg);
+ break;
+
+ case OLDI_SINGLE_LINK_DUPLICATE_MODE:
+ oldi_cfg |= BIT(5); /* DUPLICATE MODE */
+ dispc_vp_write(dispc, hw_videoport, DISPC_VP_DSS_OLDI_CFG, oldi_cfg);
+ dispc_vp_write(dispc, hw_videoport + 1, DISPC_VP_DSS_OLDI_CFG, oldi_cfg);
+ break;
+
+ case OLDI_DUAL_LINK:
+ oldi_cfg |= BIT(11); /* DUALMODESYNC */
+ dispc_vp_write(dispc, hw_videoport, DISPC_VP_DSS_OLDI_CFG, oldi_cfg);
+ dispc_vp_write(dispc, hw_videoport + 1, DISPC_VP_DSS_OLDI_CFG, oldi_cfg);
+ break;
+
+ default:
+ dev_warn(dispc->dev, "%s: Incorrect oldi mode. Returning.\n",
+ __func__);
+ return;
+ }
while (!(oldi_reset_bit & dispc_read(dispc, DSS_SYSSTATUS)) &&
count < 10000)
This feels a bit hacky:
- The function is dispc_enable_oldi, but the above code also disables
oldi. We have code in dispc_vp_unprepare() which disables OLDI at the
moment.
- The function takes hw_videoport as a parameter, and is designed to
work on that videoport. The above operates on two videoports. Isn't the
function also called for hw_videoport +1, which would result in reg
writes to hw_videoport + 2?
- No matching code in dispc_vp_unprepare
Obviously the duplicate mode (I presume that's "cloning") and the dual
link complicate things here, and I have to say I haven't worked with
such setups. But I think somehow this should be restructured so that
common configuration (common to the OLDIs) is done somewhere else.
I would guess that there are other drivers that support cloning and dual
mode. Did you have a look how they handle things?
Tomi
