Le sam. 15 juin 2024 à 02:47, Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx> a écrit : > > On Fri, Jun 14, 2024 at 04:54:47PM +0200, Julien Stephan wrote: > > Le ven. 14 juin 2024 à 16:43, Laurent Pinchart a écrit : > > > On Fri, Jun 14, 2024 at 04:14:52PM +0200, Julien Stephan wrote: > > > > Le ven. 14 juin 2024 à 14:34, Laurent Pinchart a écrit : > > > > > On Fri, Jun 14, 2024 at 12:38:15PM +0200, Julien Stephan wrote: > > > > > > Le mer. 12 juin 2024 à 10:06, AngeloGioacchino Del Regno a écrit : > > > > > > > > > > > > > > Il 10/06/24 16:39, Julien Stephan ha scritto: > > > > > > [...] > > > > > > > >> > > > > > > > >>> + writel(0x10001, input->base + SENINF_TG1_SEN_CK); > > > > > > > >> > > > > > > > >> Unroll this one... this is the TG1 sensor clock divider. > > > > > > > >> > > > > > > > >> CLKFL GENMASK(5, 0) > > > > > > > >> CLKRS GENMASK(13, 8) > > > > > > > >> CLKCNT GENMASK(21,16) > > > > > > > >> > > > > > > > >> Like this, I don't get what you're trying to set, because you're using a fixed > > > > > > > >> sensor clock rate, meaning that only a handful of camera sensors will be usable. > > > > > > > >> > > > > > > > >> Is this 8Mhz? 16? 24? what? :-) > > > > > > > >> > > > > > > > >> Two hints: > > > > > > > >> - sensor_clk = clk_get_rate(isp_clk) / (tg1_sen_ck_clkcnt + 1); > > > > > > > >> - int mtk_seninf_set_sensor_clk(u8 rate_mhz); > > > > > > > >> > > > > > > > >> Please :-) > > > > > > > > > > > > > > > > Hi Angelo, > > > > > > > > > > > > > > > > I think I get your point about not hardcoding the sensor rate, but I > > > > > > > > am not sure how to use > > > > > > > > a mtk_seninf_set_sensor_clk(u8 rate_mhz); function. > > > > > > > > > > > > > > > > Where would it be called? How is it exposed to the user? > > > > > > > > > > > > > > > > > > > > > > As for where: setup, streaming start, resolution change (which may be covered > > > > > > > by streaming start anyway, as a change should be calling stop->start anyway). > > > > > > > > > > > > > > And for the how is it exposed to the user - well, depends what you mean for user, > > > > > > > but it's all standard V4L2 API :-) > > > > > > > > > > > > > > Last but not least, I can give you another hint.... > > > > > > > > > > > > > > struct media_entity *entity = (something_here); > > > > > > > struct media_pad *mpad; > > > > > > > struct v4l2_subdev *cam_subdev; > > > > > > > struct v4l2_ctrl *ctl; > > > > > > > s64 link_frequency, pixel_clock; > > > > > > > > > > > > > > if (entity->pads[0].flags & MEDIA_PAD_FL_SINK) > > > > > > > return -E_NOT_A_CAMERA_SENSOR_WE_IGNORE_THIS_ONE; > > > > > > > > > > > > > > pad = media_pad_remote_pad_first(&entity->pads[0]); > > > > > > > if (!pad) > > > > > > > return -ENOENT; > > > > > > > > > > > > > > if (!is_media_entity_v4l2_subdev(pad->entity)) > > > > > > > return -ENOENT; > > > > > > > > > > > > > > if (pad->entity->function != MEDIA_ENT_F_CAM_SENSOR) > > > > > > > return -ENOENT; > > > > > > > > > > > > > > > > > > > Hi Angelo, > > > > > > > > > > > > Thank you for the detailed explanation :) > > > > > > However, I can't make it work because in my case, seninf is connected > > > > > > to an external ISP > > > > > > so pad->entity->function == MEDIA_ENT_F_PROC_VIDEO_ISP. > > > > > > > > > > > > How can I get the pad corresponding to the sensor? > > > > > > > > > > You don't have to. You can drop that check, and get the link frequency > > > > > of the source subdev with v4l2_get_link_freq(), whatever it is. > > > > > > > > > > > > cam_subdev = media_entity_to_v4l2_subdev(pad->entity); > > > > > > > ctl = v4l2_ctrl_find(subdev->ctrl_handler, V4L2_CID_PIXEL_RATE); > > > > > > > > > > > > Is this mandatory to implement V4L2_CID_PIXEL_RATE ? > > > > > > Should I return an error if not found? > > > > > > > > > > Does SENINF need to know both the pixel rate and link frequency ? > > > > > V4L2_CID_PIXEL_RATE is very ill-defined, at the moment it only makes > > > > > sense as a value relative to the sensor pixel array, and doesn't really > > > > > apply further down in the pipeline. What information do you need to > > > > > program the SENINF ? > > > > > > > > Hi Laurent, > > > > > > > > I need to know the clock divider for the sensor > > > > > > Could you provide some details on how the SENINF uses that divisor ? > > > What does it control, and what are the constraints ? > > > > According to the datasheet, SENINF_TG1_SEN_CK[21:16] :CLKCNT : Sensor > > master clock will be ISP_clock/(CLKCNT+1) where CLKCNT >= 1 > > I'll need more information. My guess so far is that there's a FIFO > somewhere in the SENINF, with the pixel bus clocked by the CSI-2 clock > before the FIFO, and by the "Sensor master clock" after the FIFO. Is > that right ? If so, the simplest approach would be to use the link > frequency to compute the pixel clock before the FIFO, and make sure that > the sensor master clock will be larger than or equal to that. > > A better approach from a power consumption point of view would be to > consider horizontal blanking. The FIFO can fill faster than it gets > emptied during the active portion of the line and then drain during > blanking. This allows for a slower clock on the output side. You will > need to pick an output clock frequency that > > - on average is larger than the number of active pixels per line divided > by the line duration ; and > > - ensures the FIFO never overflows during the active portion of the line, > for cases where the line length is larger than the FIFO size. > Hi Laurent and Angelo, Thank you for your help on this. I just sent a v5 with such a function. But it seems like changing this register has no effect. I asked some feedback from mediatek's app engineer but they are OoO until 16/7. I am waiting for them. Cheers Julien > > > > > > > /* multiplier is usually bits per pixel, divider is usually num of lanes */ > > > > > > > link_frequency = v4l2_get_link_freq(cam_subdev->ctrl_handler, multiplier, divider); > > > > > > > pixel_clock = v4l2_ctrl_g_ctrl_int64(ctl); > > > > > > > > > > > > How to know the sensor clock given link_frequency and pixel_clock? > > > > > > Can you point me to drivers doing something similar? > > > > > > > > > > > > > > > > > > > > ....now you know what the sensor wants, set the seninf sensor clock accordingly. > > > > > > > > > > > > > > Cheers > > > > > > > Angelo > > > > > > > > > > > > > [...] > > -- > Regards, > > Laurent Pinchart
