From mboxrd@z Thu Jan 1 00:00:00 1970 From: InKi Dae Subject: Re: [PATCH] fixed sparkling issue on lcd panel when fb_blank mode is changed. Date: Mon, 22 Mar 2010 13:48:10 +0900 Message-ID: <90b950fc1003212148h5fd0359ay3e21a99b0c16387a@mail.gmail.com> References: <90b950fc1003182136n73d54c2di4be84f16e4c3534f@mail.gmail.com> <1269004294.4292.18.camel@rex> <90b950fc1003212018h69bb0fa0t9dd62815b08eb7b3@mail.gmail.com> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary=001636ed6ce36612b304825c67fc Return-path: In-Reply-To: <90b950fc1003212018h69bb0fa0t9dd62815b08eb7b3@mail.gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: To: Richard Purdie Cc: Andrew Morton , Pavel Machek , Kyungmin Park , linux-fbdev-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org --001636ed6ce36612b304825c67fc Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable I has modified my patch. this patch would change order only in case of FB_BLANK_POWERDOWN with Richard's opinion. if requested blank mode is less then FB_BLANK_POWERDOWN then it would call device specific fb_blank and then fb_notifer_call_chan otherwise fb_notifier_call_chain first, this case means power up and display controller should become on earlier then other devices like lcd panel. Please review this path again. signed-off-by : InKi Dae Best Regards, InKi Dae. 2010/3/22 InKi Dae : > yes, you are right. > > when fb_blank mode is changed to FB_BLANK_NORMAL or > FB_BLANK_UNBLANK(power down -> power up) > it has a possibility that we would encounter same issue. > > I'd try to modify my patch to be considered with your opinion and will > send it again. > Thank you for your answer. > > Best Regards, > InKi Dae. > > 2010/3/19 Richard Purdie : >> Hi, >> >> On Fri, 2010-03-19 at 13:36 +0900, InKi Dae wrote: >>> This issue is a problem that lcd panel is spakled when fb_blank mode is= changed >>> From FB_BLANK_UNBLANK to FB_BLANK_POWER or FB_BLANK_POWER to FB_BLANK_U= NBLANK. >>> >>> In case of FB_BLANK_UNBLANK, screen =3D on, vsync =3D on, hsync =3D on = and >>> For FB_BLANK_POWERDOWN screen =3D blanked, vsync =3D off, hsync =3D off >>> So like this when fb_blank mode becomes FB_BLANK_POWERDOWN, >>> Display controller and lcd panel should become off to reduce power cons= umption. >>> >>> Let's see fb_blank function of fbmem.c file. >>> >>> fb_blank() >>> { >>> =A0 =A0 if (info->fbops->fb_blank) >>> =A0 =A0 =A0 =A0 =A0 =A0 ret =3D info->fbops->fb_blank(blank, info( >>> =A0 =A0 if (!ret) >>> =A0 =A0 =A0 =A0 =A0 =A0 fb_notifier_call_chain(FB_EVENT_BLANK, &event); >>> } >>> >>> This problem is because this code calls fb_blank (fb_blank of device >>> specific framebuffer driver) >>> Earlier then fb_notifier_call_chain. >>> >>> For example, >>> Device specific fb_blank function is registered to generic framebuffer >>> driver through register_framebuffer function >>> And fb_notifier_call_chain calls any callback function registered to >>> lcd class(lcd.c) through fb_notifier_callback function. >>> So if fb_blank mode is changed to FB_BLANK_POWERDOWN then display >>> controller would become off(clock disable) >>> On the other hand, lcd panel would still be on. at this time, some >>> situation on lcd panel occers like sparkling >>> Because video clock to be delivered to ldi module of lcd panel is disab= led also. >>> >>> This patch get fb_notifier_call_chain to be called earlier then fb_blan= k. >>> Please, review this patch. >> >> So to summarise the problem more succinctly the LCD and the display >> controllers power off in the wrong order causing visual defects >> (sparkling) on the display. >> >> I was a bit worried about event order and loops with this change so I >> checked and there are three consumers of these events in the kernel: >> consoles, LCD and backlight. None of them have a problem with this >> change of order for power down so from that point of view I'm ok with >> the change. >> >> However this function also covers powerup from a screen blank to an >> active screen. When powering up it makes sense to power up the video >> device first, then the LCD, backlight and console as per the current >> code, otherwise I can imagine "sparkling" upon powerup. >> >> So it looks like we need to change order only on powerdown, not upon >> resume, otherwise we'll get further regression reports on poweron? >> >> Cheers, >> >> Richard >> >> >> >> >> > --001636ed6ce36612b304825c67fc Content-Type: application/octet-stream; name="fbmem.patch" Content-Disposition: attachment; filename="fbmem.patch" Content-Transfer-Encoding: base64 X-Attachment-Id: f_g72s636p0 ZGlmZiAtLWdpdCBhL2RyaXZlcnMvdmlkZW8vZmJtZW0uYyBiL2RyaXZlcnMvdmlkZW8vZmJtZW0u YwppbmRleCBhMTViNDRlLi5kODBlMDk3IDEwMDY0NAotLS0gYS9kcml2ZXJzL3ZpZGVvL2ZibWVt LmMKKysrIGIvZHJpdmVycy92aWRlby9mYm1lbS5jCkBAIC0xMDA3LDI0ICsxMDA3LDMzIEBAIGZi X3NldF92YXIoc3RydWN0IGZiX2luZm8gKmluZm8sIHN0cnVjdCBmYl92YXJfc2NyZWVuaW5mbyAq dmFyKQogCiBpbnQKIGZiX2JsYW5rKHN0cnVjdCBmYl9pbmZvICppbmZvLCBpbnQgYmxhbmspCi17 CQotIAlpbnQgcmV0ID0gLUVJTlZBTDsKK3sKKwlzdHJ1Y3QgZmJfZXZlbnQgZXZlbnQ7CisJaW50 IHJldCA9IC1FSU5WQUw7CiAKLSAJaWYgKGJsYW5rID4gRkJfQkxBTktfUE9XRVJET1dOKQotIAkJ YmxhbmsgPSBGQl9CTEFOS19QT1dFUkRPV047CisJaWYgKGJsYW5rID4gRkJfQkxBTktfUE9XRVJE T1dOKQorCQlibGFuayA9IEZCX0JMQU5LX1BPV0VSRE9XTjsKIAotCWlmIChpbmZvLT5mYm9wcy0+ ZmJfYmxhbmspCi0gCQlyZXQgPSBpbmZvLT5mYm9wcy0+ZmJfYmxhbmsoYmxhbmssIGluZm8pOwor CWV2ZW50LmluZm8gPSBpbmZvOworCWV2ZW50LmRhdGEgPSAmYmxhbms7CiAKLSAJaWYgKCFyZXQp IHsKLQkJc3RydWN0IGZiX2V2ZW50IGV2ZW50OworCWlmIChibGFuayA8ICBGQl9CTEFOS19QT1dF UkRPV04pIHsKKwkJaWYgKGluZm8tPmZib3BzLT5mYl9ibGFuaykKKwkJCXJldCA9IGluZm8tPmZi b3BzLT5mYl9ibGFuayhibGFuaywgaW5mbyk7CiAKLQkJZXZlbnQuaW5mbyA9IGluZm87Ci0JCWV2 ZW50LmRhdGEgPSAmYmxhbms7Ci0JCWZiX25vdGlmaWVyX2NhbGxfY2hhaW4oRkJfRVZFTlRfQkxB TkssICZldmVudCk7CisJCXJldCA9IGZiX25vdGlmaWVyX2NhbGxfY2hhaW4oRkJfRVZFTlRfQkxB TkssICZldmVudCk7CisJCWlmICgocmV0ICYgTk9USUZZX1NUT1BfTUFTSykgPT0gTk9USUZZX1NU T1BfTUFTSykKKwkJCXByaW50ayhLRVJOX0VSUiAibm90aWZpZXJfY2FsbCBmYWlsZWQuXG4iKTsK Kwl9IGVsc2UgeworCQlyZXQgPSBmYl9ub3RpZmllcl9jYWxsX2NoYWluKEZCX0VWRU5UX0JMQU5L LCAmZXZlbnQpOworCQlpZiAoKHJldCAmIE5PVElGWV9TVE9QX01BU0spID09IE5PVElGWV9TVE9Q X01BU0spCisJCQlwcmludGsoS0VSTl9FUlIgIm5vdGlmaWVyX2NhbGwgZmFpbGVkLlxuIik7CisK KwkJaWYgKGluZm8tPmZib3BzLT5mYl9ibGFuaykKKwkJCXJldCA9IGluZm8tPmZib3BzLT5mYl9i bGFuayhibGFuaywgaW5mbyk7CiAJfQogCi0gCXJldHVybiByZXQ7CisJcmV0dXJuIHJldDsKIH0K IAogc3RhdGljIGxvbmcgZG9fZmJfaW9jdGwoc3RydWN0IGZiX2luZm8gKmluZm8sIHVuc2lnbmVk IGludCBjbWQsCg== --001636ed6ce36612b304825c67fc--