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: 1) non-continuous mode with messages transmitted in low-power mode 2) non-continuous mode with messages transmitted in high-speed mode 3) continuous mode with messages transmitted in low-power mode 4) continuous mode with messages transmitted in high-speed mode What other cases do you think we need to support? Thierry
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