| Message ID | 20120717140140.GC3850@renkinjitsu.usine.8d.com (mailing list archive) |
|---|---|
| State | New, archived |
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[CC'ing OMAPDSS matinainer] On 17 July 2012 19:31, Raphael Assenat <raph@8d.com> wrote: > Add timings for ChiMei G121S1-L01/L02 and G121X1-L01 LCD displays. > Display panels are board specific and there is no limit to the number of panels that could be connected to omap dss. Does it make sense to get panel params via DT? Or at least have them come from board file? (esp when there is hardly a panel shared by two boards, and some panels aren't even used by any board in mainline) -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Hi, On Tuesday 17 July 2012 09:57 PM, Jassi Brar wrote: > [CC'ing OMAPDSS matinainer] > > On 17 July 2012 19:31, Raphael Assenat <raph@8d.com> wrote: >> Add timings for ChiMei G121S1-L01/L02 and G121X1-L01 LCD displays. >> > Display panels are board specific and there is no limit to the number > of panels that could be connected to omap dss. > Does it make sense to get panel params via DT? Or at least have them > come from board file? (esp when there is hardly a panel shared by two > boards, and some panels aren't even used by any board in mainline) > A panel specific param should stay in the panel driver, it's something which is specific to the panel and not the platform it is in, things like the gpio reset number, i2c connections with the panel etc would make sense to come via DT/board file. It's true that currently omap platforms don't share the same panels, but there is no stopping us to do that. We could remove the default panel and attach a new one, even though we won't upstream non default panels in the DT/board file, it would be always easier to make this change in software if most of the panel specific info stays in the panel driver. Also, 2 platforms of different SoC's may use the same panel. Currently the panel drivers are SoC specific, but there is work being done between different display maintainers so that the same panel driver works across different SoCs. Archit -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 20 July 2012 13:41, Archit Taneja <a0393947@ti.com> wrote: > On Tuesday 17 July 2012 09:57 PM, Jassi Brar wrote: >>> >>> Add timings for ChiMei G121S1-L01/L02 and G121X1-L01 LCD displays. >>> >> Display panels are board specific and there is no limit to the number >> of panels that could be connected to omap dss. >> Does it make sense to get panel params via DT? Or at least have them >> come from board file? (esp when there is hardly a panel shared by two >> boards, and some panels aren't even used by any board in mainline) >> > > A panel specific param should stay in the panel driver, it's something which > is specific to the panel and not the platform it is in > Yes it is board specific, but no it should not stay in the driver. The driver simply needs one compatible set of 15 numbers to do its job. Let me explain my point in detail.... The array generic_dpi_panels[] is but a limited list of compatible configurations of a 'generic' panel. Each occupying ~20 lines in kernel. There would be dozens of supported panels that exist but are not listed in this array, and countless more that are possible to manufacture. If I submit a 2000 lines patch with only 100 such configurations you would have no reason to reject other than "I know what you mean" :) > It's true that currently omap platforms don't share the same panels, but > there is no stopping us to do that. We could remove the default panel and > attach a new one, even though we won't upstream non default panels in the > DT/board file, it would be always easier to make this change in software if > most of the panel specific info stays in the panel driver. > You mean you want to hardcode parameters in the driver instead of modifying the dtb that you pass to the kernel? > Also, 2 platforms of different SoC's may use the same panel. Currently the > panel drivers are SoC specific, but there is work being done between > different display maintainers so that the same panel driver works across > different SoCs. > Doesn't that make the case for DT/platform_data even stronger? Of course you as a maintainer have the final say. I am out of ways to explain my point. Cheers. -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Friday 20 July 2012 05:43 PM, Jassi Brar wrote: > On 20 July 2012 13:41, Archit Taneja <a0393947@ti.com> wrote: >> On Tuesday 17 July 2012 09:57 PM, Jassi Brar wrote: >>>> >>>> Add timings for ChiMei G121S1-L01/L02 and G121X1-L01 LCD displays. >>>> >>> Display panels are board specific and there is no limit to the number >>> of panels that could be connected to omap dss. >>> Does it make sense to get panel params via DT? Or at least have them >>> come from board file? (esp when there is hardly a panel shared by two >>> boards, and some panels aren't even used by any board in mainline) >>> >> >> A panel specific param should stay in the panel driver, it's something which >> is specific to the panel and not the platform it is in >> > Yes it is board specific, but no it should not stay in the driver. The > driver simply needs one compatible set of 15 numbers to do its job. I agree that the panel on the 'current' platform just needs the 15 numbers. The older way how this was done was to have a separate driver for each such panel. There used to be a ton of panel driver c files doing almost the same thing, having only these 15 parameters different. This was merged into one generic driver, with each panel's properties as an element of the array. > > Let me explain my point in detail.... > The array generic_dpi_panels[] is but a limited list of compatible > configurations of a 'generic' panel. Each occupying ~20 lines in > kernel. There would be dozens of supported panels that exist but are > not listed in this array, and countless more that are possible to > manufacture. If I submit a 2000 lines patch with only 100 such > configurations you would have no reason to reject other than "I know > what you mean" :) I think I get what you mean now. You are saying that we should create a struct/member in DT which supports this class of dumb DPI panels. You are sort of reducing the panel to a set of parameters like resolution, hsync/vsync polarities. It sort of makes sense, but this will be exclusive to such dumb DPI panels. The moment a panel becomes more complex, for example, have it's own register set, I guess we would need to have keep those properties in the panel driver, rather than DT. I don't know much about DT. But are there other devices which are completely represented by DT? For example, would a keypad/keyboard's parameters be totally represented in the DT blob, i.e, the number of keys, the mappings etc? > >> It's true that currently omap platforms don't share the same panels, but >> there is no stopping us to do that. We could remove the default panel and >> attach a new one, even though we won't upstream non default panels in the >> DT/board file, it would be always easier to make this change in software if >> most of the panel specific info stays in the panel driver. >> > You mean you want to hardcode parameters in the driver instead of > modifying the dtb that you pass to the kernel? I meant that, but if we go with your approach, which sort of makes sense now, it would be in the dtb file. > >> Also, 2 platforms of different SoC's may use the same panel. Currently the >> panel drivers are SoC specific, but there is work being done between >> different display maintainers so that the same panel driver works across >> different SoCs. >> > Doesn't that make the case for DT/platform_data even stronger? > > Of course you as a maintainer have the final say. I am out of ways to > explain my point. I get your point now. You are generalising/reducing a panel as a set of properties which can be linked to a platform. I didn't think of it that way. One little negative I see with this approach though is the integrity of the panel parameters in the dtb file. If a person working on a new platform has a panel that's already in the 'list', he/she would only need to specify the name, and be assured that the driver has the right parameters to configure it. With the dtb way, if the person feeds a wrong value in the dtb, say an incorrect resolution, we'll be in trouble. But as I said, it's a little negative, it's not our fault if the dtb writer of the platform makes mistakes :) I am not the maintainer, Tomi is :), we could wait for his comments once he's back from vacation. Thanks, Archit -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 20 July 2012 18:14, Archit Taneja <a0393947@ti.com> wrote: > On Friday 20 July 2012 05:43 PM, Jassi Brar wrote: >> >>> It's true that currently omap platforms don't share the same panels, but >>> there is no stopping us to do that. We could remove the default panel and >>> attach a new one, even though we won't upstream non default panels in the >>> DT/board file, it would be always easier to make this change in software >>> if >>> most of the panel specific info stays in the panel driver. >>> >> You mean you want to hardcode parameters in the driver instead of >> modifying the dtb that you pass to the kernel? > > I meant that, but if we go with your approach, which sort of makes sense > now, it would be in the dtb file. > In dtb or via platform_data until we have common DT bindings. I have sent a patch doing it via platform_data, which maybe taken as such or after making it prettier to taste. Thanks. -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Tue, 2012-07-17 at 21:57 +0530, Jassi Brar wrote: > [CC'ing OMAPDSS matinainer] > > On 17 July 2012 19:31, Raphael Assenat <raph@8d.com> wrote: > > Add timings for ChiMei G121S1-L01/L02 and G121X1-L01 LCD displays. > > > Display panels are board specific and there is no limit to the number > of panels that could be connected to omap dss. > Does it make sense to get panel params via DT? Or at least have them > come from board file? (esp when there is hardly a panel shared by two > boards, and some panels aren't even used by any board in mainline) So we have two options, with pros and cons: 1) Have the configuration for countless panels specified in the driver - Pro: driver for the device is the right place to define hardcoded device properties - Pro: panels can be easily used from the board file, just define the name of the panel - Pro: the same panel can be easily used from multiple board files, without duplicating the configs - Con: Adds lines to the kernel (not really a con, all features add lines to the kernel. and we can restructure the data to fit fewer lines.) - Con: We could have "leftover" panel data, not used by anyone. 2) Have the configuration for countless panels specified in the DT data - Con: DT data is not the right place to describe device's internal hardcoded properties. DT data should be about HW connections and configurable options. - Con: Adds lines to the DT data What were the pros for option 2? I didn't really see them in this mail thread, except moving lines from the kernel to the DT, which I don't really see as a pro. Tomi
On 31 July 2012 13:21, Tomi Valkeinen <tomi.valkeinen@ti.com> wrote: > 2) Have the configuration for countless panels specified in the DT data > Why should a DT blob for a board contain more than 1 panel configuration? -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Tue, 2012-07-31 at 13:33 +0530, Jassi Brar wrote: > On 31 July 2012 13:21, Tomi Valkeinen <tomi.valkeinen@ti.com> wrote: > > > 2) Have the configuration for countless panels specified in the DT data > > > Why should a DT blob for a board contain more than 1 panel configuration? I meant the DT data generally, for all boards. Tomi
On 31 July 2012 13:44, Tomi Valkeinen <tomi.valkeinen@ti.com> wrote: > On Tue, 2012-07-31 at 13:33 +0530, Jassi Brar wrote: >> On 31 July 2012 13:21, Tomi Valkeinen <tomi.valkeinen@ti.com> wrote: >> >> > 2) Have the configuration for countless panels specified in the DT data >> > >> Why should a DT blob for a board contain more than 1 panel configuration? > > I meant the DT data generally, for all boards. > If you mean : Why have the configuration (those 15 integers) of the panel on a board specified in board.dtb? Well, that is an important purpose of DT - moving board specific parameters, on which a generic code works, out of kernel (I am refraining from preaching the goodness of that). -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Tue, 2012-07-31 at 13:57 +0530, Jassi Brar wrote: > On 31 July 2012 13:44, Tomi Valkeinen <tomi.valkeinen@ti.com> wrote: > > On Tue, 2012-07-31 at 13:33 +0530, Jassi Brar wrote: > >> On 31 July 2012 13:21, Tomi Valkeinen <tomi.valkeinen@ti.com> wrote: > >> > >> > 2) Have the configuration for countless panels specified in the DT data > >> > > >> Why should a DT blob for a board contain more than 1 panel configuration? > > > > I meant the DT data generally, for all boards. > > > If you mean : Why have the configuration (those 15 integers) of the > panel on a board specified in board.dtb? > Well, that is an important purpose of DT - moving board specific > parameters, on which a generic code works, out of kernel (I am > refraining from preaching the goodness of that). Sure. But panel's unconfigurable properties are not board specific parameters, they are panel's internal stuff. It doesn't matter to which board I attach Acme Foo-123 panel, the panel timings are still the same. Okay, agreed, the timing properties are not unconfigurable. But I'd expect that normally the timings used are the normal timings specified in the panel's datasheet. For the cases where the board manufacturer wants to use non-standard timings, perhaps we could allow overriding with DT data the ones specified in the kernel. Or have a panel driver that expects to get all the data from DT. But I don't see why a panel database in the kernel driver is a bad thing (presuming it can be used in most cases). The driver should allow using the panel device without requiring the user to give extra information. (extra in the sense that the driver should already know about that info). Tomi
On 31 July 2012 14:12, Tomi Valkeinen <tomi.valkeinen@ti.com> wrote: > On Tue, 2012-07-31 at 13:57 +0530, Jassi Brar wrote: >> On 31 July 2012 13:44, Tomi Valkeinen <tomi.valkeinen@ti.com> wrote: >> > On Tue, 2012-07-31 at 13:33 +0530, Jassi Brar wrote: >> >> On 31 July 2012 13:21, Tomi Valkeinen <tomi.valkeinen@ti.com> wrote: >> >> >> >> > 2) Have the configuration for countless panels specified in the DT data >> >> > >> >> Why should a DT blob for a board contain more than 1 panel configuration? >> > >> > I meant the DT data generally, for all boards. >> > >> If you mean : Why have the configuration (those 15 integers) of the >> panel on a board specified in board.dtb? >> Well, that is an important purpose of DT - moving board specific >> parameters, on which a generic code works, out of kernel (I am >> refraining from preaching the goodness of that). > > Sure. But panel's unconfigurable properties are not board specific > parameters, they are panel's internal stuff. It doesn't matter to which > board I attach Acme Foo-123 panel, the panel timings are still the same. > It's not about the panel, it's about the board. For the generic driver in the kernel , the 'panel' is just a set of 15 integer values. There's no "Acme Foo-123" or "Acme Bar-123". In fact, the _only_ purpose of the panel's name string in the driver is to pick the correct set of "15 integers". With DT, the name string would be unnecessary. Consider two panels "ABC_123" and "XYZ_321" having identical parameters but different internals. Would you have duplicate elements in the generic_dpi_panels[] array ? Because the 'panels' are different. Or would you simply assume the XYZ_Board has the panel 'ABC_123'? Because after all it's the parameters that matter. In short, we should see a 'panel' simply as a set of 15 integers. -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Tue, 2012-07-31 at 14:27 +0530, Jassi Brar wrote: > On 31 July 2012 14:12, Tomi Valkeinen <tomi.valkeinen@ti.com> wrote: > > On Tue, 2012-07-31 at 13:57 +0530, Jassi Brar wrote: > >> On 31 July 2012 13:44, Tomi Valkeinen <tomi.valkeinen@ti.com> wrote: > >> > On Tue, 2012-07-31 at 13:33 +0530, Jassi Brar wrote: > >> >> On 31 July 2012 13:21, Tomi Valkeinen <tomi.valkeinen@ti.com> wrote: > >> >> > >> >> > 2) Have the configuration for countless panels specified in the DT data > >> >> > > >> >> Why should a DT blob for a board contain more than 1 panel configuration? > >> > > >> > I meant the DT data generally, for all boards. > >> > > >> If you mean : Why have the configuration (those 15 integers) of the > >> panel on a board specified in board.dtb? > >> Well, that is an important purpose of DT - moving board specific > >> parameters, on which a generic code works, out of kernel (I am > >> refraining from preaching the goodness of that). > > > > Sure. But panel's unconfigurable properties are not board specific > > parameters, they are panel's internal stuff. It doesn't matter to which > > board I attach Acme Foo-123 panel, the panel timings are still the same. > > > It's not about the panel, it's about the board. For the generic driver > in the kernel , the 'panel' is just a set of 15 integer values. > There's no "Acme Foo-123" or "Acme Bar-123". In fact, the _only_ > purpose of the panel's name string in the driver is to pick the > correct set of "15 integers". With DT, the name string would be > unnecessary. Yes, the panel's name is used to "probe" the correct config. If we had panels that could be asked "which panel are you" we could use that, but with dummy panels we need to manually give the identifier (name) so that the driver can do the probe. > Consider two panels "ABC_123" and "XYZ_321" having identical > parameters but different internals. > Would you have duplicate elements in the generic_dpi_panels[] array ? > Because the 'panels' are different. > Or would you simply assume the XYZ_Board has the panel 'ABC_123'? > Because after all it's the parameters that matter. I would duplicate the elements. Or, if we have lots of panels having the exact same parameters, we could have an array of names instead of just a name. > In short, we should see a 'panel' simply as a set of 15 integers. Ok, I see. You mean that the 15 integers define the panel, so, in a sense, the 15 integers is the name/identifier for the panel. It would technically work, of course. But I do disagree with it: 1) I still don't see why you say it's board related. The properties in question are properties of the panel, told in the panel specs, and programmed when using the panel. No matter where the panel is used, the same properties should be used. 2) As I see it, describing non-configurable device hardware properties in the DT data is the wrong way. The driver should either probe the properties or an ID from the device, or the ID of the device should be given to the driver (a bit like what can be done with i2c). 3) Moving the data to DT would make any future changes more difficult. Say, we could (probably should) add some regulator handling to the driver, because usually panels need power to operate. Currently we just presume the powers are always on. Adding this is easy with the current approach. Adding it if the data is in DT would be difficult, if not impossible, as all the board out there could already be using the old DT format which doesn't have the regulator data. Even in the best case all the boards out there would not be able to use the regulator stuff. Academic issues aside, what is the issue with the current approach in practice? How would the DT approach make it better? Both approaches work just fine, afaik. The current approach requires some maintenance from me, but that's rather minor. Anyway, even if I don't see the point, I'm not strictly against your approach. If everybody thinks it's much better, it's fine for me. We're currently discussing a platform agnostic approach to panel drivers with some other SoC guys, I'll raise this question. However, I don't want to apply the patch to move the properties to board files. We're gonna move to DT anyway, and that patch would be just extra stuff. Tomi
On 31 July 2012 15:27, Tomi Valkeinen <tomi.valkeinen@ti.com> wrote: > On Tue, 2012-07-31 at 14:27 +0530, Jassi Brar wrote: >> On 31 July 2012 14:12, Tomi Valkeinen <tomi.valkeinen@ti.com> wrote: >> > On Tue, 2012-07-31 at 13:57 +0530, Jassi Brar wrote: >> >> On 31 July 2012 13:44, Tomi Valkeinen <tomi.valkeinen@ti.com> wrote: >> >> > On Tue, 2012-07-31 at 13:33 +0530, Jassi Brar wrote: >> >> >> On 31 July 2012 13:21, Tomi Valkeinen <tomi.valkeinen@ti.com> wrote: >> >> >> >> >> >> > 2) Have the configuration for countless panels specified in the DT data >> >> >> > >> >> >> Why should a DT blob for a board contain more than 1 panel configuration? >> >> > >> >> > I meant the DT data generally, for all boards. >> >> > >> >> If you mean : Why have the configuration (those 15 integers) of the >> >> panel on a board specified in board.dtb? >> >> Well, that is an important purpose of DT - moving board specific >> >> parameters, on which a generic code works, out of kernel (I am >> >> refraining from preaching the goodness of that). >> > >> > Sure. But panel's unconfigurable properties are not board specific >> > parameters, they are panel's internal stuff. It doesn't matter to which >> > board I attach Acme Foo-123 panel, the panel timings are still the same. >> > >> It's not about the panel, it's about the board. For the generic driver >> in the kernel , the 'panel' is just a set of 15 integer values. >> There's no "Acme Foo-123" or "Acme Bar-123". In fact, the _only_ >> purpose of the panel's name string in the driver is to pick the >> correct set of "15 integers". With DT, the name string would be >> unnecessary. > > Yes, the panel's name is used to "probe" the correct config. If we had > panels that could be asked "which panel are you" we could use that, but > with dummy panels we need to manually give the identifier (name) so that > the driver can do the probe. > >> Consider two panels "ABC_123" and "XYZ_321" having identical >> parameters but different internals. >> Would you have duplicate elements in the generic_dpi_panels[] array ? >> Because the 'panels' are different. >> Or would you simply assume the XYZ_Board has the panel 'ABC_123'? >> Because after all it's the parameters that matter. > > I would duplicate the elements. Or, if we have lots of panels having the > exact same parameters, we could have an array of names instead of just a > name. > >> In short, we should see a 'panel' simply as a set of 15 integers. > > Ok, I see. You mean that the 15 integers define the panel, so, in a > sense, the 15 integers is the name/identifier for the panel. > > It would technically work, of course. But I do disagree with it: > > 1) I still don't see why you say it's board related. The properties in > question are properties of the panel, told in the panel specs, and > programmed when using the panel. No matter where the panel is used, the > same properties should be used. > > 2) As I see it, describing non-configurable device hardware properties > in the DT data is the wrong way. The driver should either probe the > properties or an ID from the device, or the ID of the device should be > given to the driver (a bit like what can be done with i2c). > > 3) Moving the data to DT would make any future changes more difficult. > Say, we could (probably should) add some regulator handling to the > driver, because usually panels need power to operate. Currently we just > presume the powers are always on. > > Adding this is easy with the current approach. Adding it if the data is > in DT would be difficult, if not impossible, as all the board out there > could already be using the old DT format which doesn't have the > regulator data. Even in the best case all the boards out there would not > be able to use the regulator stuff. > > > Academic issues aside, what is the issue with the current approach in > practice? How would the DT approach make it better? Both approaches work > just fine, afaik. The current approach requires some maintenance from > me, but that's rather minor. > > Anyway, even if I don't see the point, I'm not strictly against your > approach. If everybody thinks it's much better, it's fine for me. > No, I don't insist. Its only I in 'everybody' here, so please do it only if you see any merit in passing panel parameters via DT. I only wanted to share my opinion and so I did. Best Regards. -jassi -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
--- a/drivers/video/omap2/displays/panel-generic-dpi.c +++ b/drivers/video/omap2/displays/panel-generic-dpi.c @@ -486,6 +486,80 @@ static struct panel_config generic_dpi_panels[] = { OMAP_DSS_LCD_IHS | OMAP_DSS_LCD_IPC, .name = "primeview_pd104slf", }, + + /* ChiMei G121S1-L01 */ + { + { + .x_res = 800, + .y_res = 600, + + .pixel_clock = 39700, + + .hfp = 128, + .hsw = 1, + .hbp = 128, + + .vfp = 28, + .vsw = 1, + .vbp = 28 + }, + .acbi = 0x0, + .acb = 0x0, + .config = OMAP_DSS_LCD_TFT, + .power_on_delay = 0, + .power_off_delay = 0, + .name = "chimei_g121s1-l01", + }, + + /* ChiMei G121S1-L02 */ + { + { + .x_res = 800, + .y_res = 600, + + .pixel_clock = 40000, + + .hfp = 1, + .hsw = 256, + .hbp = 1, + + .vfp = 1, + .vsw = 28, + .vbp = 1 + }, + .acbi = 0x0, + .acb = 0x0, + .config = OMAP_DSS_LCD_TFT, + .power_on_delay = 0, + .power_off_delay = 0, + .name = "chimei_g121s1-l02", + }, + + + /* ChiMei G121X1-L01 */ + { + { + .x_res = 1024, + .y_res = 768, + + .pixel_clock = 64900, + + .hfp = 160, + .hsw = 1, + .hbp = 160, + + .vfp = 38, + .vsw = 1, + .vbp = 38 + }, + .acbi = 0x0, + .acb = 0x0, + .config = OMAP_DSS_LCD_TFT, + .power_on_delay = 0, + .power_off_delay = 0, + .name = "chimei_g121x1-l01", + }, + }; struct panel_drv_data {
Add timings for ChiMei G121S1-L01/L02 and G121X1-L01 LCD displays. Signed-off-by: Raphael Assenat <raph@8d.com> -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html