On Mon, Aug 11, 2014 at 05:15:35PM +0900, Inki Dae wrote: > 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? Yes, if the MIPI_DSI_MODE_NON_CONTINUOUS flag is not specified, then it means the peripheral supports only continuous mode. Thierry
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