[U-Boot] [PATCH 15/17] sunxi: Ippo_q8h defconfigs: Enable the LCD panel found on these tablets.

[Hans de Goede]

Hi,

On 30-12-14 11:18, Siarhei Siamashka wrote:
> On Thu, 25 Dec 2014 11:59:55 +0100
> Hans de Goede <hdegoede at redhat.com> wrote:
>
>> Hi,
>>
>> On 25-12-14 11:00, Chen-Yu Tsai wrote:
>>> Hi,
>>>
>>> On Thu, Dec 25, 2014 at 3:06 AM, Hans de Goede <hdegoede at redhat.com> wrote:
>>>> Enable the new LCD support on Ippo_q8h tablets.
>>>>
>>>> Signed-off-by: Hans de Goede <hdegoede at redhat.com>
>>>> ---
>>>>    configs/Ippo_q8h_v1_2_defconfig | 5 ++++-
>>>>    configs/Ippo_q8h_v5_defconfig   | 5 ++++-
>>>>    2 files changed, 8 insertions(+), 2 deletions(-)
>>>>
>>>> diff --git a/configs/Ippo_q8h_v1_2_defconfig b/configs/Ippo_q8h_v1_2_defconfig
>>>> index fefed32..c773f5f 100644
>>>> --- a/configs/Ippo_q8h_v1_2_defconfig
>>>> +++ b/configs/Ippo_q8h_v1_2_defconfig
>>>> @@ -1,7 +1,10 @@
>>>>    CONFIG_SPL=y
>>>>    CONFIG_SYS_EXTRA_OPTIONS="CONS_INDEX=5"
>>>>    CONFIG_FDTFILE="sun8i-a23-ippo-q8h-v1.2.dtb"
>>>> -CONFIG_VIDEO=n
>>>> +CONFIG_VIDEO_LCD_MODE="x:800,y:480,depth:18,pclk_khz:33000,le:16,ri:209,up:22,lo:22,hs:30,vs:1,sync:0,vmode:0"
>>>> +CONFIG_VIDEO_LCD_POWER="PH7"
>>>> +CONFIG_VIDEO_LCD_BL_EN="PH6"
>>>> +CONFIG_VIDEO_LCD_BL_PWM="PH0"
>>>>    CONFIG_USB_KEYBOARD=n
>>>>    +S:CONFIG_ARM=y
>>>>    +S:CONFIG_ARCH_SUNXI=y
>>>> diff --git a/configs/Ippo_q8h_v5_defconfig b/configs/Ippo_q8h_v5_defconfig
>>>> index b8d3afe..ce4f0b8 100644
>>>> --- a/configs/Ippo_q8h_v5_defconfig
>>>> +++ b/configs/Ippo_q8h_v5_defconfig
>>>> @@ -1,7 +1,10 @@
>>>>    CONFIG_SPL=y
>>>>    CONFIG_SYS_EXTRA_OPTIONS="CONS_INDEX=5"
>>>>    CONFIG_FDTFILE="sun8i-a23-ippo-q8h-v5.dtb"
>>>> -CONFIG_VIDEO=n
>>>> +CONFIG_VIDEO_LCD_MODE="x:800,y:480,depth:18,pclk_khz:33000,le:16,ri:209,up:22,lo:22,hs:30,vs:1,sync:0,vmode:0"
>>>
>>> The display on my Q8H is a bit off to the left. With the simplefb
>>> bindings from your kernel sunxi-wip branch, I get a nice console.
>>> Though I've no way to type, at least I can tell my tablet is on. :)
>>>
>>> Could you briefly explain how to convert the values in the fex
>>> file to the mode line here? It could also help others with
>>> enabling display on their tablets.
>>
>> Ah yes, I used the slightly different timings from the olimex 7" lcd
>> panel for olinuxino boards, and since those worked fine on my a23
>> tablet I never adjusted things. Here is a translation table:
>>
>>
>> CONFIG_VIDEO_LCD_MODE		fex value(s)
>>
>> x				lcd_x
>> y				lcd_y
>> depth:18			lcd_frm = 1
>> pclk_khz			lcd_dclk_freq * 1000
>> hs				lcd_hv_hspw (with a minimum of 1)
>> vs				lcd_hv_vspw (with a minimum of 1)
>> le				lcd_hbp - hs
>> ri				lcd_ht - lcd_x - lcd_hbp
>> up				lcd_vbp - vs
>>
>> On sun4i/sun5i/sun7i:
>> lo				(lcd_vt / 2) - lcd_y - lcd_vbp
>> On sun8i:
>> lo				lcd_vt - lcd_y - lcd_vbp
>>
>> sync				0
>> mode				0
>>
>> I notice that the Ippo_q8h_v5 fex uses 0 for lcd_hv_hspw and lcd_hv_vspw, which
>> is not a valid value as the register value contains hspw - 1, so the minimum is 1,
>> and looking at a register dump under android with my A23 tablet the value indeed
>> should be 1.
>
> That's interesting. What would be the correct general formula for the
> hs/vs values then? "max(lcd_hv_hspw, 1)" or maybe "lcd_hv_hspw + 1"?

Looking at the register values set by android vs the fex file, the correct
formula is "max(lcd_hv_hspw, 1)".

> BTW, I have done a preliminary automatic conversion for all FEX
> files from sunxi-boards, which enable lcd0 in fex. The results are
> now available at the all the same http://linux-sunxi.org/LCD wiki page.

Cool, thanks for doing this!

> If "hs = lcd_hv_hspw + 1" is a better choice, then the whole table
> probably needs to be re-generated.
>
> Also additional explanations about GPIO related options (what would be
> the exact rules to interpret FEX?) and more details about "lcd_frm" and
> "lcd_if" would help a lot to get a better understanding about what
> still needs to be done to get LCD displays supported on all devices.

Currently basically only lcd_if = 0 and lcd_frm = 1 are supported, it
should be possible to add support for other lcd_frm = x values easily,
so if you encounter those let me know, lcd_if != 0 is going to be much
harder to support and currently is not on my schedule.

> If I understand it correctly, the kernel sources from the Allwinner SDK
> contain the relevant code for handling the information from FEX, and
> this code is the best reference. And it's more reliable to refer to
> A23 SDK for interpreting the FEX files originally snatched from A23
> devices, and likewise A31 SDK for A31 devices. For example, it is not
> uncommon to see both 'lcd_pwm_used' and 'lcd_pwm_not_used' variables
> defined in FEX. And sometimes the values of these variables even
> contradict each other. So the fine details about the relative
> priorities of these variables and other similar things might need
> to be discovered for perfectly correct conversion.

All I can say here is that I agree with the above, I'm afraid I'm not
familiar enough with the (quite large) sunxi display code in the SDK
kernels to provide answers here.

Regards,

Hans