| Message ID | 20190322051759.15007-6-tomli@tomli.me (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | implement 2D acceleration, minor cleanups, doc updates. | expand |
On Fri, Mar 22, 2019 at 01:17:57PM +0800, Yifeng Li wrote: > This commits add information about 32-bit color, 2D acceleration, > as well as adding additional, general information about the hardware > and many existing problems of the sm712fb driver. > > Signed-off-by: Yifeng Li <tomli@tomli.me> > --- > Documentation/fb/sm712fb.txt | 123 +++++++++++++++++++++++++++++++---- > 1 file changed, 110 insertions(+), 13 deletions(-) > > diff --git a/Documentation/fb/sm712fb.txt b/Documentation/fb/sm712fb.txt > index c388442edf51..906b48aa40e4 100644 > --- a/Documentation/fb/sm712fb.txt > +++ b/Documentation/fb/sm712fb.txt > @@ -1,31 +1,128 @@ > What is sm712fb? > ================= > > -This is a graphics framebuffer driver for Silicon Motion SM712 based processors. > +"sm712fb" is a graphics framebuffer driver for Silicon Motion SM710 (LynxEM), > +SM712 (LynxEM+), and SM720 (Lynx3DM, Lynx3DM+, aka. LynxEM4+) series of > +video controllers. This series of video controller is a legacy from ~1998, > +and was used on many classic, "prehistoric" laptops from 1998-2004, such as > +IBM Thinkpad S30 and 240X. It was also used on some servers, industrial > +computers, x86 and non-x86 embedded devices where only basic graphics was > +needed. I think this is wrong. Loongson 3A Notebook was released around 2011-2012 and had SM712. > + > +Notably, Lemote YeeLoong 8089, a MIPS laptop based on the Chinese Loongson <snip> > + * More VGA modes. > * dual-head support > + * hardware cursor support > + > +The first feature is planned to be implemented soon, but the maintainer > +does not receive any monetary or hardware support from any company or OEMs, > +and he has to purchase a test platform personally. The 1998's hardware > +still costs 200 USD+, so don't expected an ETA. If you have a Big-Endian > +platform and willing to help testing, please contact the maintainer, thanks! I am not sure why will you want to mention about monetary or hardware support. Maintainers are supposed to work voluntarily. > + > +Other VGA modes, dual-head, or hardware cursor support should be possible to > +implement, but parts of the code must be rewritten, and there's little demand > +for them on this legacy (retro?) platform, so there's no plan to implement them. > +If you have a genuine need for them, please contact the maintainers. If there is any need for new features then I think the plan should be to make a drm driver. > + > +Maintainers > +================ > + > +This driver is maintained by > + > + * Tom Li <tomli@tomli.me> ?? I didn't know this. MAINTAINERS file doesnot say so. > + * Sudip Mukherjee <sudipm.mukherjee@gmail.com> > + * Teddy Wang <teddy.wang@siliconmotion.com> > + > +Tom Li was the last contributor of this driver who implemented 2D acceleration, > +and is the main author of this documentation, please send any bug reports or > +requests to Tom, but don't forget to CC other maintainers as well to make everyone > +be informed. There is a MAINTAINERS file to list the maintainers. There is no need to add that in documentation. -- Regards Sudip
On Sun, Mar 31, 2019 at 07:54:28PM +0100, Sudip Mukherjee wrote: > On Fri, Mar 22, 2019 at 01:17:57PM +0800, Yifeng Li wrote: > > +video controllers. This series of video controller is a legacy from ~1998, > > +and was used on many classic, "prehistoric" laptops from 1998-2004, such as > > +IBM Thinkpad S30 and 240X. It was also used on some servers, industrial > > +computers, x86 and non-x86 embedded devices where only basic graphics was > > +needed. > > I think this is wrong. Loongson 3A Notebook was released around 2011-2012 > and had SM712. "This series of video controller is a legacy from ~1998 and was used on many classic, prehistoric laptops from 1998-2004" is an objective fact. Even if they have been used on newer hardware, it doesn't automatically make the original statement false. But I agree that the description gives incomplete information, I think this paragraph should be reworded for clarity. I would change the description to, > "sm712fb" is a graphics framebuffer driver for Silicon Motion SM710 (LynxEM), SM712 (LynxEM+), and SM720 (Lynx3DM, Lynx3DM+, aka. LynxEM4+) series of video controllers. > This series of video controllers is a legacy product from ~1998, they are designed to be primarily used on low-power mobile systems running Windows 95/ 98/NT/2000, some examples are HP OmniBook XE2 (2000), Panasonic TOUGHBook 28 (2002), FLORA 210W NL3 (2003), Sony Vaio VGN-U50 (2004) OQO Model 01 (2004). > After 2004, they continued to be used on some non-x86 systems, including PowerPC and MIPS. It also saw applications on embedded devices, servers, industrial computers, embedded devices, where low-power operation and/or only basic graphics was needed. > Notably, Lemote YeeLoong 8089, a MIPS laptop based on the Chinese Loongson [...] I think it would be enough. BTW, most Loongson 3A notebooks don't use SM712. I don't know that there are Loongson 3A notebooks that are still using SM712 graphics chip, do you have one? Could you tell me its model number? > > +The first feature is planned to be implemented soon, but the maintainer > > +does not receive any monetary or hardware support from any company or OEMs, > > +and he has to purchase a test platform personally. The 1998's hardware > > +still costs 200 USD+, so don't expected an ETA. If you have a Big-Endian > > +platform and willing to help testing, please contact the maintainer, thanks! > > I am not sure why will you want to mention about monetary or hardware > support. Maintainers are supposed to work voluntarily. I agree, I will reword it. > > +Other VGA modes, dual-head, or hardware cursor support should be possible to > > +implement, but parts of the code must be rewritten, and there's little demand > > +for them on this legacy (retro?) platform, so there's no plan to implement them. > > +If you have a genuine need for them, please contact the maintainers. > > If there is any need for new features then I think the plan should be to > make a drm driver. That's the plan. I will reword. > There is a MAINTAINERS file to list the maintainers. There is no need to > add that in documentation. I see. Thanks, Tom Li
On Mon, Apr 1, 2019 at 6:30 PM Tom Li <tomli@tomli.me> wrote: > > On Sun, Mar 31, 2019 at 07:54:28PM +0100, Sudip Mukherjee wrote: > > On Fri, Mar 22, 2019 at 01:17:57PM +0800, Yifeng Li wrote: > > > +video controllers. This series of video controller is a legacy from ~1998, > > > +and was used on many classic, "prehistoric" laptops from 1998-2004, such as > > > +IBM Thinkpad S30 and 240X. It was also used on some servers, industrial > > > +computers, x86 and non-x86 embedded devices where only basic graphics was > > > +needed. <snip> > > BTW, most Loongson 3A notebooks don't use SM712. I don't know that there are > Loongson 3A notebooks that are still using SM712 graphics chip, do you have one? > Could you tell me its model number? No, I donot have them. I only have SM712 based PCI card which I purchased from Silicon Motion.
diff --git a/Documentation/fb/sm712fb.txt b/Documentation/fb/sm712fb.txt index c388442edf51..906b48aa40e4 100644 --- a/Documentation/fb/sm712fb.txt +++ b/Documentation/fb/sm712fb.txt @@ -1,31 +1,128 @@ What is sm712fb? ================= -This is a graphics framebuffer driver for Silicon Motion SM712 based processors. +"sm712fb" is a graphics framebuffer driver for Silicon Motion SM710 (LynxEM), +SM712 (LynxEM+), and SM720 (Lynx3DM, Lynx3DM+, aka. LynxEM4+) series of +video controllers. This series of video controller is a legacy from ~1998, +and was used on many classic, "prehistoric" laptops from 1998-2004, such as +IBM Thinkpad S30 and 240X. It was also used on some servers, industrial +computers, x86 and non-x86 embedded devices where only basic graphics was +needed. + +Notably, Lemote YeeLoong 8089, a MIPS laptop based on the Chinese Loongson +2F MIPS processor, is also using this chip because of hardware constraints, +and at a time, somewhat popular in the free software community due the +fact that it was the first laptop powered exclusively by free software, +and it was also an inexpensive platform for non-x86 hobbyists to explore. How to use it? ============== -Switching modes is done using the video=sm712fb:... boot parameter. - -If you want, for example, enable a resolution of 1280x1024x24bpp you should -pass to the kernel this command line: "video=sm712fb:0x31B". +You should not compile-in vesafb, since SM7xx can be used in a VGA +compatible mode, resulting conflicts with this driver. In addition, +the VGA compatible mode was never tested by the maintainers. -You should not compile-in vesafb. +Currently, the driver supports 3 modes: 640x480, 800x600, 1024x768, +at 16, 24 or 32-bit depth. Switching modes is done using the +`video=sm712fb:0x___` boot parameter. If you want, for example, +enable a resolution of 1280x1024x24bpp, you should pass to the kernel +this command line: "video=sm712fb:0x31B". -Currently supported video modes are: +Please consult the following table for the hexadecimal codes of +different modes. [Graphic modes] -bpp | 640x480 800x600 1024x768 1280x1024 -----+-------------------------------------------- - 8 | 0x301 0x303 0x305 0x307 - 16 | 0x311 0x314 0x317 0x31A - 24 | 0x312 0x315 0x318 0x31B +bpp | 640x480 800x600 1024x768 +----+--------------------------- + 16 | 0x311 0x314 0x317 + 24 | 0x312 0x315 0x318 + 32 | 0x329 0x32E 0x338 + +32-bit is really 8:8:8:8, but the final 8-bit number is an "empty" +alpha channel, it's otherwise equal to 24-bit color. However, they +could still be useful. For example, "fbterm" supports 32-bit mode +but not 24-bit mode. + +Notes about Modesetting +======================== + +The modesetting code in sm712fb has major problems. + +* Switching to 8-bit color mode will result in a black screen, so +they are removed from the list of supported graphic modes. But they +can still be switched to on-the-fly, don't do that then! + +* Only a refresh rate of 60 Hz is supported. + +* 1024x768 with 16-bit color is not really supported, because the +registers have been hacked by the original developer to adapt +the 1024x600 screen on Lemote YeeLoong 8089. + +* If you are using a Lemote YeeLoong 8089, please remember that only +the 1024x768 modes are guaranteed to drive the LCD panel properly. +Other modes are meant to drive a CRT, and may drive the LCD incorrectly +and result in a white screen with random garbage. External VGA output is +unaffected. + +Due to the way registers are hardcoded, it's impossible to fix them +without a major code rewrite. If you've been hit by these problems badly +and really need to get them fixed, please contact the driver maintainers. + +2D acceleration +============== + +Without 2D acceleration, the framebuffer suffers from extremely low performance, +even scrolling a single line of text on the console required an unaccelerated +screen redraw. Thus, 2D acceleration is enable by default. However, currently +it's only supported on SM710/712 with Little-Endian CPUs. Big-endian and +SM720 devices are currently not supported. + +2D acceleration can be controlled using the `video=sm712fb:accel:1` parameter. +The default option, "1" activate 2D acceleration. If you have problems, you can +set "0" to disable it. Different options can be separated by a comma, for +example, "video=sm712fb:0x31B,accel:0" set the resolution to 1280x1024x24bpp +while disabling the 2D acceleration. + +Although it has been extensively tested by the maintainer, 2D acceleration +in 24-bit color mode may still have minor issues. If you've encounter any +screen glitches in 24-bit mode in Linux framebuffer the framebuffer, don't +hurry disabling it, you should try switching to 32-bit mode first, normally +it should fix the problem. If you can reliably reproduce the screen glitches, +please report your method to the maintainers. Missing Features ================ (alias TODO list) - * 2D acceleratrion +The following features are not implemented in this driver, + + * 2D acceleration on SM720 and Big-Endian CPUs. + * More VGA modes. * dual-head support + * hardware cursor support + +The first feature is planned to be implemented soon, but the maintainer +does not receive any monetary or hardware support from any company or OEMs, +and he has to purchase a test platform personally. The 1998's hardware +still costs 200 USD+, so don't expected an ETA. If you have a Big-Endian +platform and willing to help testing, please contact the maintainer, thanks! + +Other VGA modes, dual-head, or hardware cursor support should be possible to +implement, but parts of the code must be rewritten, and there's little demand +for them on this legacy (retro?) platform, so there's no plan to implement them. +If you have a genuine need for them, please contact the maintainers. + +Maintainers +================ + +This driver is maintained by + + * Tom Li <tomli@tomli.me> + * Sudip Mukherjee <sudipm.mukherjee@gmail.com> + * Teddy Wang <teddy.wang@siliconmotion.com> + +Tom Li was the last contributor of this driver who implemented 2D acceleration, +and is the main author of this documentation, please send any bug reports or +requests to Tom, but don't forget to CC other maintainers as well to make everyone +be informed.
This commits add information about 32-bit color, 2D acceleration, as well as adding additional, general information about the hardware and many existing problems of the sm712fb driver. Signed-off-by: Yifeng Li <tomli@tomli.me> --- Documentation/fb/sm712fb.txt | 123 +++++++++++++++++++++++++++++++---- 1 file changed, 110 insertions(+), 13 deletions(-)