simple-framebuffer enquire

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);
        if (!info->screen_base) {
                ret = -ENOMEM;
                goto error_fb_release;

Another question is

        aliases {
                display0 = &lcdif;
        };

        chosen {
                #address-cells = <1>;
                #size-cells = <1>;
                ranges;

                stdout-path = &uart1;
                framebuffer0: framebuffer@86fd6080 {
                        compatible = "simple-framebuffer";
                        reg = <0x86fd6080 (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>;
                };
        };
};

How do you ensure that regulators that are bind to gpios can be
maintain during boot?
A small minor comment is how to automatic switch then to normal
framebuffer. Anyway seems
that
                #address-cells = <1>;
                #size-cells = <1>;
                ranges;

are mandatory and they are in the dts documentation.

Best regards
Michael

Hi,

On 25-06-18 15:29, Michael Nazzareno Trimarchi wrote:

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.

         if (!info->screen_base) {
                 ret = -ENOMEM;
                 goto error_fb_release;

Another question is

         aliases {
                 display0 = &lcdif;
         };

         chosen {
                 #address-cells = <1>;
                 #size-cells = <1>;
                 ranges;

                 stdout-path = &uart1;
                 framebuffer0: framebuffer@86fd6080 {
                         compatible = "simple-framebuffer";
                         reg = <0x86fd6080 (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>;

This looks like GPIOS to me why are you modeling this a supplies?

Anyways ...

                         display = <&lcdif>;
                 };
         };
};

How do you ensure that regulators that are bind to gpios can be
maintain during boot?

Any regulators listed in the simplefb dt-node will be kept enabled
until remove_conflicting_framebuffers is called() from the native
display driver. To keep them enabled while loading the native
display driver, you should get and enable them in the native display
driver *before* calling remove_conflicting_framebuffers()
(and the same goes for the clocks).

Regards,

Hans

A small minor comment is how to automatic switch then to normal
framebuffer. Anyway seems
that
                 #address-cells = <1>;
                 #size-cells = <1>;
                 ranges;

are mandatory and they are in the dts documentation.

Best regards
Michael