On Wed, Apr 24, 2024 at 2:49 PM Dmitry Baryshkov <dmitry.barysh...@linaro.org> wrote: > > On Thu, 25 Apr 2024 at 00:04, Doug Anderson <diand...@google.com> wrote: > > > > Hi, > > > > On Tue, Apr 23, 2024 at 2:20 PM Dmitry Baryshkov > > <dmitry.barysh...@linaro.org> wrote: > > > > > > On Tue, Apr 23, 2024 at 01:41:59PM -0700, Doug Anderson wrote: > > > > Hi, > > > > > > > > On Tue, Apr 23, 2024 at 11:10 AM Hsin-Yi Wang <hsi...@google.com> wrote: > > > > > > > > > > > > > > +#define _INIT_DCS_CMD(...) { \ > > > > > > > > > + .type = INIT_DCS_CMD, \ > > > > > > > > > + .len = sizeof((char[]){__VA_ARGS__}), \ > > > > > > > > > + .data = (char[]){__VA_ARGS__} } > > > > > > > > > + > > > > > > > > > +#define _INIT_DELAY_CMD(...) { \ > > > > > > > > > + .type = DELAY_CMD,\ > > > > > > > > > + .len = sizeof((char[]){__VA_ARGS__}), \ > > > > > > > > > + .data = (char[]){__VA_ARGS__} } > > > > > > > > > > > > > > > > This is the third panel driver using the same appoach. Can you > > > > > > > > use > > > > > > > > mipi_dsi_generic_write_seq() instead of the huge table? Or if > > > > > > > > you prefer > > > > > > > > the table, we should extract this framework to a common helper. > > > > > > > > (my preference is shifted towards mipi_dsi_generic_write_seq()). > > > > > > > > > > > > > > > The drawback of mipi_dsi_generic_write_seq() is that it can cause > > > > > > > the > > > > > > > kernel size grows a lot since every sequence will be expanded. > > > > > > > > > > > > > > Similar discussion in here: > > > > > > > https://lore.kernel.org/dri-devel/CAD=FV=Wju3WS45=EpXMUg7FjYDh3-=mvm_js7tf1tsaazbb...@mail.gmail.com/ > > > > > > > > > > > > > > This patch would increase the module size from 157K to 572K. > > > > > > > scripts/bloat-o-meter shows chg +235.95%. > > > > > > > > > > > > > > So maybe the common helper is better regarding the kernel module > > > > > > > size? > > > > > > > > > > > > Yes, let's get a framework done in a useful way. > > > > > > I'd say, drop the _INIT_DELAY_CMD. msleep() and usleep_range() > > > > > > should be > > > > > > used instead (and it's up to the developer to select correct delay > > > > > > function). > > > > > > > > > > > > > > > > > > > > > > + > > > > > > > > > +static const struct panel_init_cmd > > > > > > > > > kingdisplay_kd101ne3_init_cmd[] = { > > > > > > > > > + _INIT_DELAY_CMD(50), > > > > > > > > > + _INIT_DCS_CMD(0xE0, 0x00), > > > > > > > > > > > > [skipped the body of the table] > > > > > > > > > > > > > > > + _INIT_DCS_CMD(0x0E, 0x48), > > > > > > > > > + > > > > > > > > > + _INIT_DCS_CMD(0xE0, 0x00), > > > > > > > > > > > > > > > + _INIT_DCS_CMD(0X11), > > > > > > > > > > > > Also, at least this is mipi_dsi_dcs_exit_sleep_mode(). > > > > > > > > > > > > > > > + /* T6: 120ms */ > > > > > > > > > + _INIT_DELAY_CMD(120), > > > > > > > > > + _INIT_DCS_CMD(0X29), > > > > > > > > > > > > And this is mipi_dsi_dcs_set_display_on(). > > > > > > > > > > > > Having a single table enourages people to put known commands into > > > > > > the > > > > > > table, the practice that must be frowned upon and forbidden. > > > > > > > > > > > > We have functions for some of the standard DCS commands. So, maybe > > > > > > instead of adding a single-table based approach we can improve > > > > > > mipi_dsi_generic_write_seq() to reduce the bloat. E.g. by moving the > > > > > > error handling to a common part of enable() / prepare() function. > > > > > > > > > > > > > > > > For this panel, I think it can also refer to how > > > > > panel-kingdisplay-kd097d04.c does. Create the table for init cmd data, > > > > > not what operation to use, and use mipi_dsi_generic_write_seq() when > > > > > looping through the table. > > > > > > > > Even more similar discussion: > > > > > > > > https://lore.kernel.org/r/CAD=FV=ugdbnvamjzwsovxybgikqcvw9jsrtbxhvg8_97ype...@mail.gmail.com > > > > > > It seems I skipped that thread. > > > > > > I'd still suggest a code-based solution compared to table-based one, for > > > the reasons I've outlined before. Having a tables puts a pressure on the > > > developer to put commands there for which we already have a > > > command-specific function. > > > > The problem is that with these panels that need big init sequences the > > code based solution is _a lot_ bigger. If it were a few bytes or a > > 1-2KB then fine, but when Hsin-Yi measured Linus W's attempt to move > > from a table to code it was 100K difference in code [1]. I would also > > say that having these long init sequences done as separate commands > > encourages people to skip checking the return values of each of the > > transfer functions and I don't love that idea. > > > > It would be ideal if these panels didn't need these long init > > sequences, but I don't have any inside knowledge here saying that they > > could be removed. So assume we can't get rid of the init sequences it > > feels like we have to find some way to make the tables work for at > > least the large chunks of init code and encourage people to make the > > tables readable... > > > I did a quick check on the boe-tv101wum-nl6 driver by converting the > writes to use the following macro: > > #define mipi_dsi_dcs_write_cmd_seq(dsi, cmd, seq...) > \ > do { > \ > static const u8 d[] = { cmd, seq }; \ > ret = mipi_dsi_dcs_write_buffer(dsi, d, ARRAY_SIZE(d)); \ > if (ret < 0) > \ > goto err; > \ > } while (0) > > And then at the end of the init funciton having > > err: > dev_err(panel->dev, > "failed to write command %d\n", ret); > return ret; > } >
I'm not sure about the coding style rule here, would it be considered unclear that caller of mipi_dsi_dcs_write_cmd_seq() needs to have err block, but the block may not be directly used in that caller and is only jumped from the macro? > Size comparison: > text data bss dec hex filename > before > 34109 10410 18 44537 adf9 > ../build-64/drivers/gpu/drm/panel/panel-boe-tv101wum-nl6.o > making init data const > 44359 184 0 44543 adff > ../build-64/drivers/gpu/drm/panel/panel-boe-tv101wum-nl6.o > with new macros > 44353 184 0 44537 adf9 > ../build-64/drivers/gpu/drm/panel/panel-boe-tv101wum-nl6.o > > As you can see, there is literally no size difference with this macro in > place. > The only drawback is that the init stops on the first write rather > than going through the sequence. > > WDYT? I can turn this into a proper patch if you think this makes sense. > > > > > > > [1] > > https://lore.kernel.org/r/CAD=FV=UFa_AoJQvUT3BTiRs19WCA2xLVeQOU=+nyu_hae0_...@mail.gmail.com > > > > -- > With best wishes > Dmitry