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From:   Michael Nazzareno Trimarchi <michael@amarulasolutions.com>
Date:   Tue, 26 Jun 2018 18:35:09 +0200
Message-ID: <CAOf5uwmxZxxKG0CnstnNaTYdt-1+=YZHr8eSac5TdwfANdobxQ@mail.gmail.com>
Subject: Re: simple-framebuffer enquire
To:     Hans de Goede <hdegoede@redhat.com>
Cc:     artlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>,
        linux-fbdev@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>
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Hi Hans

On Tue, Jun 26, 2018 at 4:47 PM, Hans de Goede <hdegoede@redhat.com> wrote:
> Hi,
>
>
> On 26-06-18 16:42, Michael Nazzareno Trimarchi wrote:
>>
>> Hi Hans
>>
>> On Tue, Jun 26, 2018 at 3:38 PM, Michael Nazzareno Trimarchi
>> <michael@amarulasolutions.com> wrote:
>>>
>>> Hi
>>>
>>> On Tue, Jun 26, 2018 at 3:36 PM, Hans de Goede <hdegoede@redhat.com>
>>> wrote:
>>>>
>>>> Hi,
>>>>
>>>>
>>>> On 26-06-18 15:29, Michael Nazzareno Trimarchi wrote:
>>>>>
>>>>>
>>>>> Hi
>>>>>
>>>>> to be more specific
>>>>>
>>>>> On Tue, Jun 26, 2018 at 3:06 PM, Michael Nazzareno Trimarchi
>>>>> <michael@amarulasolutions.com> wrote:
>>>>>>
>>>>>>
>>>>>> Hi
>>>>>>
>>>>>> On Tue., 26 Jun. 2018, 12:01 pm Hans de Goede, <hdegoede@redhat.com>
>>>>>> wrote:
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> Hi,
>>>>>>>
>>>>>>> On 25-06-18 15:29, Michael Nazzareno Trimarchi wrote:
>>>>>>>>
>>>>>>>>
>>>>>>>> Hi Hans
>>>>>>>>
>>>>>>>> In order to let it even registered the simplefb I have added this
>>>>>>>> change. According on what I understand
>>>>>>>> from the code seems that this is the way to acquire memory with the
>>>>>>>> correct attribute
>>>>>>>>
>>>>>>>> diff --git a/drivers/video/fbdev/simplefb.c
>>>>>>>> b/drivers/video/fbdev/simplefb.c
>>>>>>>> index a3c44ec..7e61ce3 100644
>>>>>>>> --- a/drivers/video/fbdev/simplefb.c
>>>>>>>> +++ b/drivers/video/fbdev/simplefb.c
>>>>>>>> @@ -466,8 +466,8 @@ static int simplefb_probe(struct platform_device
>>>>>>>> *pdev)
>>>>>>>>
>>>>>>>>            info->fbops = &simplefb_ops;
>>>>>>>>            info->flags = FBINFO_DEFAULT | FBINFO_MISC_FIRMWARE;
>>>>>>>> -       info->screen_base = ioremap_wc(info->fix.smem_start,
>>>>>>>> -                                      info->fix.smem_len);
>>>>>>>> +       info->screen_base = arch_memremap_wb(info->fix.smem_start,
>>>>>>>> +                                            info->fix.smem_len);
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> I'm not sure why you need this?  wb certainly is not optimal
>>>>>>> for a framebuffer, the existing wc mapping is really what you
>>>>>>> want.
>>>>>>>
>>>>>>
>>>>>> Well in this way raise a WARN and get a nice NULL on memory remap on
>>>>>> imx6ull
>>>>>> SoC
>>>>>>
>>>>>
>>>>> [    0.397484] WARNING: CPU: 0 PID: 1 at arch/arm/mm/ioremap.c:303
>>>>> __arm_ioremap_pfn_caller+0x80/0x1cc
>>>>
>>>>
>>>>
>>>>
>>>> This is causes by a mismatch in memory attributes, which means the
>>>> memory is already mapped by the kernel as regular RAM and may
>>>> already be used for other purposes by the kernel!
>>>>
>>>> Memory used by a simplefb framebuffer must be reserved by the
>>>> bootloader, so that it does not get used by the kernel as regular
>>>> RAM. See e.g.:
>>>>
>>>>
>>>> http://git.denx.de/?p=u-boot.git;a=blob;f=drivers/video/sunxi/sunxi_display.c
>>>>
>>>> Near the end of the file where the framebuffer RAM gets excluded from
>>>> the memory-range reported to the kernel as usable RAM. Note this relies
>>>> on the u-boot sunxi video code putting the framebuffer at the end of the
>>>> RAM.
>>
>>
>> +       aliases {
>> +               display0 = &lcdif;
>> +       };
>> +
>> +       reserved-memory {
>> +               #address-cells = <1>;
>> +               #size-cells = <1>;
>> +               ranges;
>> +
>> +               display_reserved: framebuffer@86fd6080 {
>> +                       reg = <0x86fd6080 (480 * 272 *4)>;
>> +               };
>> +
>>
>> This should do the trick but I have still the same problem on memory
>> type. Any idea?
>
>
> For starters your start address and size are not page-size
> (multiple of 4k aligned), you need to fix that.
>

cat memblock/reserved
   0: 0x80004000..0x80007fff
   1: 0x80100000..0x81e030b3
   2: 0x83000000..0x83007fff
   3: 0x84000000..0x85ffffff
   4: 0x86fa2000..0x87021fff

+       reserved-memory {
+               #address-cells = <1>;
+               #size-cells = <1>;
+               ranges;
+
+               display_reserved: framebuffer@86fa2000 {
+                       reg = <0x86fa2000 0x80000>;
+               };
+
+       };
+
+       chosen {
+               #address-cells = <1>;
+               #size-cells = <1>;
+               ranges;
+
+               stdout-path = &uart1;
+               framebuffer0: framebuffer@86fa2000 {
+                       compatible = "simple-framebuffer";
+                       reg = <0x86fa2000 (480 * 272 * 4)>;
+                       width = <480>;
+                       height = <272>;
+                       stride = <(480 * 4)>;
+                       format = "a8r8g8b8";
+                       clocks = <&clks IMX6UL_CLK_LCDIF_PIX>,
+                                <&clks IMX6UL_CLK_LCDIF_APB>,
+                                <&clks IMX6UL_CLK_DUMMY>,
+                                <&clks IMX6UL_CLK_GPIO3>,
+                                <&clks IMX6UL_CLK_GPIO4>;
+                       nshut-supply = <&reg_lcd_nshut>;
+                       nreset-supply = <&reg_lcd_nreset>;
+                       display = <&lcdif>;

Still have the same on ioremap.

Michael


> After that double check in the memory map reported by the
> kernel during boot that your reservation actually works.
>
> Regards,
>
> Hans
>
>
>
>
>>
>>
>> +               linux,cma {
>> +                       compatible = "shared-dma-pool";
>> +                       reusable;
>> +                       size = <0x1000000>;
>> +                       linux,cma-default;
>> +               };
>> +       };
>> +
>> +       chosen {
>> +               #address-cells = <1>;
>> +               #size-cells = <1>;
>> +               ranges;
>> +
>> +               stdout-path = &uart1;
>> +               framebuffer0: framebuffer@86fd6080 {
>> +                       compatible = "simple-framebuffer";
>> +                       reg = <0x86fd6080 (480 * 272 * 4)>;
>>
>> Here I try to use the same. I will create in uboot a dynamic way to
>> track down. I think that
>> we can even add to the simple buffer a way to get hand of reserved
>> region automatically
>>
>> Michael
>>
>> +                       width = <480>;
>> +                       height = <272>;
>> +                       stride = <(480 * 4)>;
>> +                       format = "a8r8g8b8";
>> +                       clocks = <&clks IMX6UL_CLK_LCDIF_PIX>,
>> +                                <&clks IMX6UL_CLK_LCDIF_APB>,
>> +                                <&clks IMX6UL_CLK_DUMMY>,
>> +                                <&clks IMX6UL_CLK_GPIO3>,
>> +                                <&clks IMX6UL_CLK_GPIO4>;
>> +                       nshut-supply = <&reg_lcd_nshut>;
>> +                       nreset-supply = <&reg_lcd_nreset>;
>> +                       display = <&lcdif>;
>> +                       status = "okay";
>> +               };
>>
>>
>>
>>>>
>>>
>>> Thank you very much for this lesson ;). I will try to document better
>>> after my tour ;)
>>>
>>> Michael
>>>
>>>> Regards,
>>>>
>>>> Hans
>>>
>>>
>>>
>>>
>>> --
>>> | Michael Nazzareno Trimarchi                     Amarula Solutions BV |
>>> | COO  -  Founder                                      Cruquiuskade 47 |
>>> | +31(0)851119172                                 Amsterdam 1018 AM NL |
>>> |                  [`as] http://www.amarulasolutions.com               |
>>
>>
>>
>>
>


-- 
| Michael Nazzareno Trimarchi                     Amarula Solutions BV |
| COO  -  Founder                                      Cruquiuskade 47 |
| +31(0)851119172                                 Amsterdam 1018 AM NL |
|                  [`as] http://www.amarulasolutions.com               |