linux-kernel - simple-framebuffer enquire

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Date:   Mon, 25 Jun 2018 15:29:27 +0200
From:   Michael Nazzareno Trimarchi <michael@...rulasolutions.com>
To:     Hans de Goede <hdegoede@...hat.com>
Cc:     Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        linux-fbdev@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>
Subject: 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@...d6080 {
                        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