Hi Krzysztof,
On 09/30/2015 03:34 PM, Krzysztof
Kozlowski wrote:
On 30.09.2015 16:19, Yakir Yang wrote:
Hi Krzysztof,
On 09/30/2015 01:32 PM, Krzysztof Kozlowski wrote:
On 22.09.2015 16:37, Yakir Yang wrote:
Both hsync/vsync polarity and interlace mode can be parsed from
drm display mode, and dynamic_range and ycbcr_coeff can be judge
by the video code.
But presumably Exynos still relies on the DT properties, so take
good use of mode_fixup() in to achieve the compatibility hacks.
Signed-off-by: Yakir Yang <ykk@xxxxxxxxxxxxxx>
---
Changes in v5:
- Switch video timing type to "u32", so driver could use "of_property_read_u32"
to get the backword timing values.
Okay
Krzysztof suggest me that driver could use
the "of_property_read_bool" to get backword timing values, but that interfacs
would modify the original drm_display_mode timing directly (whether those
properties exists or not).
Hmm, I don't understand. You have a:
struct video_info {
bool h_sync_polarity;
bool v_sync_polarity;
bool interlaced;
};
so what is wrong with:
dp_video_config->h_sync_polarity =
of_property_read_bool(dp_node, "hsync-active-high");
Is it exactly the same binding as previously?
Yes, it is the same binding as previously. But just a note that we already
mark those DT binding as deprecated.
+-interlaced: deprecated prop that can parsed frm drm_display_mode.
+-vsync-active-high: deprecated prop that can parsed frm drm_display_mode.
+-hsync-active-high: deprecated prop that can parsed frm drm_display_mode.
For now those values should come from "struct drm_display_mode",
and we already parsed them out from "drm_display_mode" before
driver provide the backward compatibility.
Let's used the "hsync-active-high" example:
As for now the code would like:
static void analogix_dp_bridge_mode_set(...)
{
// Parsed timing value from "drm_display_mode"
video->h_sync_polarity = !!(mode->flags & DRM_MODE_FLAG_NHSYNC);
// Try to detect the deprecated property, providing
// the backward compatibility
of_property_read_u32(dp_node, "hsync-active-high",
&video->h_sync_polarity);
/*
* In this case, if "hsync-active-high" property haven't been
* found, then the video timing "h_sync_polarity" would keep
* no change, keeping the parsed value from "drm_display_mode"
*/
}
But if keep the "of_property_read_bool", then code would like:
static void analogix_dp_bridge_mode_set(...)
{
// Parsed timing value from "drm_display_mode"
video->h_sync_polarity = !!(mode->flags & DRM_MODE_FLAG_NHSYNC);
// Try to detect the deprecated property, providing
// the backward compatibility
video->h_sync_polarity =
of_property_read_bool(dp_node, "hsync-active-high");
/*
* In this case, if "hsync-active-high" property haven't been
* found, then the video timing "h_sync_polarity" would just
* modify to "false". That is the place we don't want, cause
* it would always modify the timing value parsed from
* "drm_display_mode"
*/
}
OK, I see the point of overwriting values from drm_display_mode. However
I think you changed the binding. I believe the of_property_read_u32()
will behave differently for such DTS:
exynos_dp {
...
hsync-active-high;
}
It will return -EOVERFLOW which means it would be broken now...
Whoops, thanks for your remind, after try that, I do see over flow
error.
static void *of_find_property_value_of_size(const struct
device_node *np,
const char *propname, u32 len)
{
....
if (len > prop->length)
return ERR_PTR(-EOVERFLOW);
...
}
So I though code should be:
if (of_property_read_bool(dp_node, "hsync-active-high"))
video->h_sync_polarity = true;
And we can't provide full backward compatibility for this property,
cause
the previous exynos_dp driver would set this timing value to "false"
when
property not defined, but analogix_dp driver keep this timing value
corresponding to "drm_display_mode" when property not found.
Thanks,
- Yakir
Best regards,
Krzysztof
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