On 2014년 08월 11일 16:50, Thierry Reding wrote:
On Mon, Aug 11, 2014 at 04:35:46PM +0900, Inki Dae wrote:
On 2014년 08월 11일 16:24, Thierry Reding wrote:
On Mon, Aug 11, 2014 at 02:19:21PM +0900, Inki Dae wrote:
On 2014년 08월 08일 18:55, Thierry Reding wrote:
[...]
The above is actually more like this:
if ((flags & MIPI_DSI_MODE_NON_CONTINUOUS) == 0) clear DSI_HS_CLK_CTRL; else set DSI_HS_CLK_CTRL;
if (msg->flags & MIPI_DSI_MSG_USE_LPM) clear DSI_HIGH_SPEED_TRANS; else set DSI_HIGH_SPEED_TRANS;
So for peripherals that don't support non-continuous clock mode, this will result in the following for low-power transmissions:
clear DSI_HS_CLK_CTRL; /* HS clock always on */ clear DSI_HIGH_SPEED_TRANS;
Right, then how host driver should check it if peripheral doesn't support non-continuous clock mode? Or how the peripheral should notify it to host driver? It would need a new flag instead of MIPI_DSI_MODE_NON_CONTINUOUS.
MIPI_DSI_MODE_NON_CONTINUOUS is exactly the flag that devices need to set to signal that they support non-continuous mode. If devices don't have that set, then the controller should always provide the HS clock.
So, if MIPI_DSI_MODE_NON_CONTINUOUS is *not* set, then the peripheral does *not* support non-continuous mode.
Again, assume that there is a peripheral that doesn't support non-continuous clock mode but host driver want to transmit data in low power. For this, you already mentioned like below,
"So for peripherals that don't support non-continuous clock mode, this will result in the following for low-power transmissions:
clear DSI_HS_CLK_CTRL; /* HS clock always on */ clear DSI_HIGH_SPEED_TRANS; "
In this case, how should host driver check it to clear above two flags? As you know, this is required to clear two flags same as non-continuous clock mode. Don't you think that we need a new flag to identify them - non-continuous clock mode or just for low-power transmission?
See what I wrote a little further up:
if ((flags & MIPI_DSI_MODE_NON_CONTINUOUS) == 0) clear DSI_HS_CLK_CTRL; else set DSI_HS_CLK_CTRL;
if (msg->flags & MIPI_DSI_MSG_USE_LPM) clear DSI_HIGH_SPEED_TRANS; else set DSI_HIGH_SPEED_TRANS;
MIPI_DSI_MODE_NON_CONTINUOUS specifies that a peripheral supports non- continuous mode. When set, we clear DSI_HS_CLK_CTRL on Tegra because that tells the controller to turn off the HS clock between high-speed transmissions.
MIPI_DSI_MSG_USE_LPM specifies that a message is to be sent in low-power mode.
With the above two flags we can cover four cases:
- non-continuous mode with messages transmitted in low-power mode
- non-continuous mode with messages transmitted in high-speed mode
- continuous mode with messages transmitted in low-power mode
In case of 3), it would mean "set DSI_HS_CLK_CTRL" and "clear DSI_HIGH_SPEED_TRANS". However, msg->flags has MIPI_DSI_MSG_USE_LPM but dsi->mode_flags has no MIPI_DSI_MODE_NON_CONTINOUS flag..... Ah, right. You mean that continuous mode is set by default implicitly?
Thanks, Inki Dae
- continuous mode with messages transmitted in high-speed mode
What other cases do you think we need to support?
Thierry