Hi On Tue, Jun 26, 2018 at 3:36 PM, Hans de Goede <hdegoede@xxxxxxxxxx> 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@xxxxxxxxxxxxxxxxxxxx> wrote: >>> >>> Hi >>> >>> On Tue., 26 Jun. 2018, 12:01 pm Hans de Goede, <hdegoede@xxxxxxxxxx> >>> 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. > 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 | -- To unsubscribe from this list: send the line "unsubscribe linux-fbdev" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
