On 7/31/23 11:21, Jason-JH Lin (林睿祥) wrote:
Hi Eugen,
Thanks for the reviews.
On Fri, 2023-07-28 at 11:47 +0300, Eugen Hristev wrote:
Hi,
On 7/27/23 19:41, Jason-JH.Lin wrote:
Add checking the length of each data path before assigning drm
private
data into all_drm_priv array.
Fixes: 1ef7ed48356c ("drm/mediatek: Modify mediatek-drm for mt8195
multi mmsys support")
Signed-off-by: Jason-JH.Lin <jason-jh.lin@xxxxxxxxxxxx>
---
drivers/gpu/drm/mediatek/mtk_drm_drv.c | 16 +++++++++++++---
1 file changed, 13 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/mediatek/mtk_drm_drv.c
b/drivers/gpu/drm/mediatek/mtk_drm_drv.c
index 249c9fd6347e..d2fb1fb4e682 100644
--- a/drivers/gpu/drm/mediatek/mtk_drm_drv.c
+++ b/drivers/gpu/drm/mediatek/mtk_drm_drv.c
@@ -351,6 +351,7 @@ static bool mtk_drm_get_all_drm_priv(struct
device *dev)
{
struct mtk_drm_private *drm_priv = dev_get_drvdata(dev);
struct mtk_drm_private *all_drm_priv[MAX_CRTC];
+ struct mtk_drm_private *temp_drm_priv;
struct device_node *phandle = dev->parent->of_node;
const struct of_device_id *of_id;
struct device_node *node;
@@ -373,9 +374,18 @@ static bool mtk_drm_get_all_drm_priv(struct
device *dev)
if (!drm_dev || !dev_get_drvdata(drm_dev))
continue;
- all_drm_priv[cnt] = dev_get_drvdata(drm_dev);
- if (all_drm_priv[cnt] && all_drm_priv[cnt]-
mtk_drm_bound)
- cnt++;
+ temp_drm_priv = dev_get_drvdata(drm_dev);
+ if (temp_drm_priv) {
+ if (temp_drm_priv->mtk_drm_bound)
+ cnt++;
+
+ if (temp_drm_priv->data->main_len)
+ all_drm_priv[0] = temp_drm_priv;
+ else if (temp_drm_priv->data->ext_len)
+ all_drm_priv[1] = temp_drm_priv;
+ else if (temp_drm_priv->data->third_len)
+ all_drm_priv[2] = temp_drm_priv;
+ }
Previously the code was assigning stuff into all_drm_priv[cnt] and
incrementing it.
With your change, it assigns to all_drm_priv[0], [1], [2]. Is this
what
you intended ?
Because dev_get_drvdata(drm_dev) will get the driver data by drm_dev.
Each drm_dev represents a display path.
e,g.
drm_dev of "mediatek,mt8195-vdosys0" represents main path.
drm_dev of "mediatek,mt8195-vdosys1" represents ext path.
So we want to make sure all_drm_priv[] store the private data in
the order of display path, such as:
all_drm_priv[0] = the private data of main display
all_drm_priv[1] = the private data of ext display
all_drm_priv[2] = the private data of third display
If you have such a hard requirement for keeping elements in an array,
you are better having
drm_priv_main_display
drm_priv_ext_display
drm_priv_third_display
Keeping them indexed in a three elements array by having no logical
connection between the number [0,1,2] and the actual displays that you
want to save is a bit confusing.
One other option which I don't know if it's better or not is to have
macros to hide your indexed approach:
all_drm_priv[MAIN_DISPLAY] ...
etc.
If this loop has second run, you will reassign to all_drm_priv again
?
Because the previous code will store all_drm_priv[] in the order of
mtk_drm_bind() was called.
If drm_dev of ext path bound earlier than drm_dev of main path,
all_drm_priv[] in mtk_drm_get_all_drm_priv() may be re-assigned like
this:
all_drm_priv[0]->all_drm_priv[0] = private data of ext path
all_drm_priv[1]->all_drm_priv[0] = private data of ext path
all_drm_priv[0]->all_drm_priv[1] = private data of main path
all_drm_priv[1]->all_drm_priv[1] = private data of main path
But we expect all_drm_priv[] be re-assigned like this:
all_drm_priv[0]->all_drm_priv[0] = private data of main path
all_drm_priv[1]->all_drm_priv[0] = private data of main path
all_drm_priv[0]->all_drm_priv[1] = private data of ext path
all_drm_priv[1]->all_drm_priv[1] = private data of ext path
This expectation does not appear to be really enforced in your code.
You have a driver that keeps an array with all_drm_priv[], in which
you can have main path or ext path. Then it's natural that they might
have whichever order in the array you are placing them into.
If you have a hard enforced order of keeping elements in your array,
then an indexed array is not the best option here.
You can either: move to a different type of array , with macros for
indexes into the array, or, store a second array/field which keeps the
index in which you saved each element.
This is just my opinion , by looking at your code.
I would expect you to take `cnt` into account.
Also, is it expected that all_drm_priv has holes in the array ?
Each drm_dev will only called mtk_drm_bind() once, so all holes
will be filled after all drm_dev has called mtk_drm_bind().
Do you agree with this statement? :)
At the moment I cannot agree nor disagree, I don't know the code well
enough. But what I can say, is that you should not rely on future calls
of the function to fill up your array correctly.
Regards,
Jason-JH.Lin
Eugen
}
if (drm_priv->data->mmsys_dev_num == cnt) {
