Messages in this thread | ![/](/images/icornerl.gif) | | Date | Wed, 27 Jul 2022 16:22:50 +0300 | Subject | Re: [PATCH 8/8] drm/tidss: Enable Dual and Duplicate Modes for OLDI | From | Tomi Valkeinen <> |
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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@ti.com> > --- > 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
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