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: > > 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 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 > 4) continuous mode with messages transmitted in high-speed mode > > What other cases do you think we need to support? > > Thierry > -- To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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