Re: [PATCH v7 1/6] drm/tidss: Remove Video Port to Output Port coupling
From: Aradhya Bhatia
Date: Sun Feb 05 2023 - 08:09:03 EST
Hi Tomi,
Thanks for the review!
On 03-Feb-23 16:53, Tomi Valkeinen wrote:
> On 25/01/2023 13:35, Aradhya Bhatia wrote:
>> Make DSS Video Ports agnostic of output bus types.
>>
>> DSS controllers have had a 1-to-1 coupling between its VPs and its
>> output ports. This no longer stands true for the new AM625 DSS. This
>> coupling, hence, has been removed by renaming the 'vp_bus_type' to
>> 'output_port_bus_type' because the VPs are essentially agnostic of the
>> bus type and it is the output ports which have a bus type.
>>
>> The AM625 DSS has 2 VPs but requires 3 output ports to support its
>> Dual-Link OLDI video output coming from a single VP.
>
> Not a biggie, but this sentence is a bit odd here at the end. Shouldn't
> it be after the "...stands true for the new AM625 DSS."?
Yes! It should be. Will make the edit.
>
>> Signed-off-by: Aradhya Bhatia <a-bhatia1@xxxxxx>
>> ---
>> drivers/gpu/drm/tidss/tidss_dispc.c | 47 +++++++++++++++++------------
>> drivers/gpu/drm/tidss/tidss_dispc.h | 21 +++++++------
>> drivers/gpu/drm/tidss/tidss_drv.h | 5 +--
>> drivers/gpu/drm/tidss/tidss_irq.h | 2 +-
>> drivers/gpu/drm/tidss/tidss_kms.c | 12 ++++----
>> 5 files changed, 48 insertions(+), 39 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/tidss/tidss_dispc.c b/drivers/gpu/drm/tidss/tidss_dispc.c
>> index 165365b515e1..c1c4faccbddc 100644
>> --- a/drivers/gpu/drm/tidss/tidss_dispc.c
>> +++ b/drivers/gpu/drm/tidss/tidss_dispc.c
>> @@ -61,7 +61,7 @@ const struct dispc_features dispc_k2g_feats = {
>> .min_pclk_khz = 4375,
>> .max_pclk_khz = {
>> - [DISPC_VP_DPI] = 150000,
>> + [DISPC_PORT_DPI] = 150000,
>> },
>> /*
>> @@ -96,7 +96,6 @@ const struct dispc_features dispc_k2g_feats = {
>> .vp_name = { "vp1" },
>> .ovr_name = { "ovr1" },
>> .vpclk_name = { "vp1" },
>> - .vp_bus_type = { DISPC_VP_DPI },
>> .vp_feat = { .color = {
>> .has_ctm = true,
>> @@ -109,6 +108,9 @@ const struct dispc_features dispc_k2g_feats = {
>> .vid_name = { "vid1" },
>> .vid_lite = { false },
>> .vid_order = { 0 },
>> +
>> + .num_output_ports = 1,
>> + .output_port_bus_type = { DISPC_PORT_DPI },
>> };
>
> Just thinking out loud, as these will get more complex in the future,
> maybe we should finally group them with struct. E.g. we could define
> struct array for vps, like (just hacky example):
>
> struct {
> const char *name;
> const char *clkname;
> struct tidss_vp_feat feat;
> } vps[TIDSS_MAX_PORTS];
>
> and then use them as:
>
> .vps = {
> {
> .name = "kala",
> .clkname = "kissa",
> .feat.color.has_ctm = true,
> }, {
> .name = "kala2",
> .clkname = "kissa2",
> .feat.color.has_ctm = false,
> },
> },
>
> Perhaps something to try in the future.
>
Yes, agreed! Having that structure will tidy this up.
I will keep this under future work.
>> static const u16 tidss_am65x_common_regs[DISPC_COMMON_REG_TABLE_LEN] = {
>> @@ -140,8 +142,8 @@ static const u16 tidss_am65x_common_regs[DISPC_COMMON_REG_TABLE_LEN] = {
>> const struct dispc_features dispc_am65x_feats = {
>> .max_pclk_khz = {
>> - [DISPC_VP_DPI] = 165000,
>> - [DISPC_VP_OLDI] = 165000,
>> + [DISPC_PORT_DPI] = 165000,
>> + [DISPC_PORT_OLDI] = 165000,
>> },
>> .scaling = {
>> @@ -171,7 +173,6 @@ const struct dispc_features dispc_am65x_feats = {
>> .vp_name = { "vp1", "vp2" },
>> .ovr_name = { "ovr1", "ovr2" },
>> .vpclk_name = { "vp1", "vp2" },
>> - .vp_bus_type = { DISPC_VP_OLDI, DISPC_VP_DPI },
>> .vp_feat = { .color = {
>> .has_ctm = true,
>> @@ -185,6 +186,9 @@ const struct dispc_features dispc_am65x_feats = {
>> .vid_name = { "vid", "vidl1" },
>> .vid_lite = { false, true, },
>> .vid_order = { 1, 0 },
>> +
>> + .num_output_ports = 2,
>> + .output_port_bus_type = { DISPC_PORT_OLDI, DISPC_PORT_DPI },
>> };
>> static const u16 tidss_j721e_common_regs[DISPC_COMMON_REG_TABLE_LEN] = {
>> @@ -229,8 +233,8 @@ static const u16 tidss_j721e_common_regs[DISPC_COMMON_REG_TABLE_LEN] = {
>> const struct dispc_features dispc_j721e_feats = {
>> .max_pclk_khz = {
>> - [DISPC_VP_DPI] = 170000,
>> - [DISPC_VP_INTERNAL] = 600000,
>> + [DISPC_PORT_DPI] = 170000,
>> + [DISPC_PORT_INTERNAL] = 600000,
>> },
>> .scaling = {
>> @@ -260,9 +264,7 @@ const struct dispc_features dispc_j721e_feats = {
>> .vp_name = { "vp1", "vp2", "vp3", "vp4" },
>> .ovr_name = { "ovr1", "ovr2", "ovr3", "ovr4" },
>> .vpclk_name = { "vp1", "vp2", "vp3", "vp4" },
>> - /* Currently hard coded VP routing (see dispc_initial_config()) */
>> - .vp_bus_type = { DISPC_VP_INTERNAL, DISPC_VP_DPI,
>> - DISPC_VP_INTERNAL, DISPC_VP_DPI, },
>> +
>
> I think this line feed is extra.
Okay! Will remove that from all SoC feat structs.
>
>> .vp_feat = { .color = {
>> .has_ctm = true,
>> .gamma_size = 1024,
>> @@ -273,6 +275,11 @@ const struct dispc_features dispc_j721e_feats = {
>> .vid_name = { "vid1", "vidl1", "vid2", "vidl2" },
>> .vid_lite = { 0, 1, 0, 1, },
>> .vid_order = { 1, 3, 0, 2 },
>> +
>> + .num_output_ports = 4,
>> + /* Currently hard coded VP routing (see dispc_initial_config()) */
>> + .output_port_bus_type = { DISPC_PORT_INTERNAL, DISPC_PORT_DPI,
>> + DISPC_PORT_INTERNAL, DISPC_PORT_DPI, },
>
> Indent doesn't look right (but it might be just because this is a diff).
I may have missed indenting this.
>
>> };
>> static const u16 *dispc_common_regmap;
>> @@ -287,12 +294,12 @@ struct dispc_device {
>> void __iomem *base_common;
>> void __iomem *base_vid[TIDSS_MAX_PLANES];
>> - void __iomem *base_ovr[TIDSS_MAX_PORTS];
>> - void __iomem *base_vp[TIDSS_MAX_PORTS];
>> + void __iomem *base_ovr[TIDSS_MAX_VPS];
>> + void __iomem *base_vp[TIDSS_MAX_VPS];
>> struct regmap *oldi_io_ctrl;
>> - struct clk *vp_clk[TIDSS_MAX_PORTS];
>> + struct clk *vp_clk[TIDSS_MAX_VPS];
>> const struct dispc_features *feat;
>> @@ -300,7 +307,7 @@ struct dispc_device {
>> bool is_enabled;
>> - struct dss_vp_data vp_data[TIDSS_MAX_PORTS];
>> + struct dss_vp_data vp_data[TIDSS_MAX_VPS];
>> u32 *fourccs;
>> u32 num_fourccs;
>> @@ -851,7 +858,7 @@ int dispc_vp_bus_check(struct dispc_device *dispc, u32 hw_videoport,
>> return -EINVAL;
>> }
>> - if (dispc->feat->vp_bus_type[hw_videoport] != DISPC_VP_OLDI &&
>> + if (dispc->feat->output_port_bus_type[hw_videoport] != DISPC_PORT_OLDI &&
>
> Hmm, so is the hw_videoport a vp index or an output index? Sounds like
> the former, so it's not right, even if at the moment they're identical.
> We need some kind of mapping between those.
>
It is indeed a vp index. And yes, I can come up with a mapping mechanism.
> If the mapping can be changed (or just defined in the DT), I think we
> need a variable in struct dispc_device, which tells the output to which
> a videoport is connected to. Or vice versa, I'm not sure which direction
> we need more. If the mapping is always the same on all SoC (but I don't
> think so), we can have it in the feats.
>
As of now, the mapping is always same. But I would like to make is
generalized for future. Hence, I am considering to keep the variable in
struct dispc_device.
My question though would be, how would one be able to find which kind
of device is the port connected to, if it is connected to a bridge? For
example, in case of panels, we have a "connector_type" variable in
drm_panel which tells what kind of sink it is. But there is no such
thing in drm_bridge.
This is required because what if we can connect an videoport to either
an LVDS/OLDI bridge or a DPI bridge.
Also, implementing this might mean removal of the part of code which
confirms that the panel's "connector_type" indeed expects what the VP
can provide, unless there is a way to find out what the sink is before
calling the drm_of_find_panel_or_bridge API.
On the direction, the primary requirement of hw_videoport has been in
the tidss_dispc.c file where the HW registers are getting configured.
'hw_videoport' is a frequently passed parameter in function calls. So,
at a first glance the former option might makes more sense for
direction, i.e. to have a variable which tells the output to which a
videoport is connected to.
And while, there is also the tidss_kms.c file, which deals with
initializing encoders and attaching bridges. This is where the
output_port is required more often. But I am yet to think of a case
where the above direction could be an issue.
> Also, I wonder if output_port is a good name as it has "port" in it
> (like video port), and it's a bit long-ish. Would just "output" be
> enough? We could, of course, shorten it to OP, but that looks odd to me =).
>
>> fmt->is_oldi_fmt) {
>> dev_dbg(dispc->dev, "%s: %s is not OLDI-port\n",
>> __func__, dispc->feat->vp_name[hw_videoport]);
>> @@ -955,7 +962,7 @@ void dispc_vp_prepare(struct dispc_device *dispc, u32 hw_videoport,
>> if (WARN_ON(!fmt))
>> return;
>> - if (dispc->feat->vp_bus_type[hw_videoport] == DISPC_VP_OLDI) {
>> + if (dispc->feat->output_port_bus_type[hw_videoport] == DISPC_PORT_OLDI) {
>> dispc_oldi_tx_power(dispc, true);
>> dispc_enable_oldi(dispc, hw_videoport, fmt);
>> @@ -1014,7 +1021,7 @@ void dispc_vp_enable(struct dispc_device *dispc, u32 hw_videoport,
>> align = true;
>> /* always use DE_HIGH for OLDI */
>> - if (dispc->feat->vp_bus_type[hw_videoport] == DISPC_VP_OLDI)
>> + if (dispc->feat->output_port_bus_type[hw_videoport] == DISPC_PORT_OLDI)
>> ieo = false;
>> dispc_vp_write(dispc, hw_videoport, DISPC_VP_POL_FREQ,
>> @@ -1040,7 +1047,7 @@ void dispc_vp_disable(struct dispc_device *dispc, u32 hw_videoport)
>> void dispc_vp_unprepare(struct dispc_device *dispc, u32 hw_videoport)
>> {
>> - if (dispc->feat->vp_bus_type[hw_videoport] == DISPC_VP_OLDI) {
>> + if (dispc->feat->output_port_bus_type[hw_videoport] == DISPC_PORT_OLDI) {
>> dispc_vp_write(dispc, hw_videoport, DISPC_VP_DSS_OLDI_CFG, 0);
>> dispc_oldi_tx_power(dispc, false);
>> @@ -1116,10 +1123,10 @@ enum drm_mode_status dispc_vp_mode_valid(struct dispc_device *dispc,
>> const struct drm_display_mode *mode)
>> {
>> u32 hsw, hfp, hbp, vsw, vfp, vbp;
>> - enum dispc_vp_bus_type bus_type;
>> + enum dispc_port_bus_type bus_type;
>> int max_pclk;
>> - bus_type = dispc->feat->vp_bus_type[hw_videoport];
>> + bus_type = dispc->feat->output_port_bus_type[hw_videoport];
>> max_pclk = dispc->feat->max_pclk_khz[bus_type];
>> diff --git a/drivers/gpu/drm/tidss/tidss_dispc.h b/drivers/gpu/drm/tidss/tidss_dispc.h
>> index e49432f0abf5..30fb44158347 100644
>> --- a/drivers/gpu/drm/tidss/tidss_dispc.h
>> +++ b/drivers/gpu/drm/tidss/tidss_dispc.h
>> @@ -50,11 +50,11 @@ struct dispc_errata {
>> bool i2000; /* DSS Does Not Support YUV Pixel Data Formats */
>> };
>> -enum dispc_vp_bus_type {
>> - DISPC_VP_DPI, /* DPI output */
>> - DISPC_VP_OLDI, /* OLDI (LVDS) output */
>> - DISPC_VP_INTERNAL, /* SoC internal routing */
>> - DISPC_VP_MAX_BUS_TYPE,
>> +enum dispc_port_bus_type {
>> + DISPC_PORT_DPI, /* DPI output */
>> + DISPC_PORT_OLDI, /* OLDI (LVDS) output */
>> + DISPC_PORT_INTERNAL, /* SoC internal routing */
>> + DISPC_PORT_MAX_BUS_TYPE,
>
> Okay, so here you have just "port", not "output_port". In the DT,
> they're ports, so... Maybe we could use that name too, and for video
> port always use "vp". The current "hw_videoport" could be easily
> mistaken with "port".
I see what you are saying and how somebody could confusre hw_videoport
for a physical connection (i.e. port). I have always understoof
hw_videoport to be a thing of the actual VP inside the SoC, but that may
be because I have been working on this, and not just trying to
understand the code from a high level.
How about if I change the output_port to "out_port"? I am okay to keep
"output" as the name to. I am saying this becuase I think, only keeping
"port" might just confuse more, as you mentioned above.
And then we can change "hw_videoport" to "vp_index", perhaps, or even
keep that as it is? Becuase if we do have a VP structure in future
like you suggested above, "vps" and "vp" would become a close overlap.
For eg, "vps[vp]".
How do these sound to you?
>
> I don't recall why I chose to use "hw" prefix there. I think I wanted to
> separate it from some other videoport, but... I don't know what that
> "other" is =).
>
Perhaps because just a "videoport" might be confused with a connector on
the board, as in "HDMI port"? And the prefix might be a way to clarify
that its the DSS controller's VP. =)
Regards
Aradhya