linux-kernel - Re: [PATCH v4 07/41] drm: handle HAS

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Date:   Tue, 16 May 2023 19:13:55 +0200
From:   Thomas Zimmermann <tzimmermann@...e.de>
To:     Niklas Schnelle <schnelle@...ux.ibm.com>,
        Arnd Bergmann <arnd@...db.de>,
        Dave Airlie <airlied@...hat.com>,
        Gerd Hoffmann <kraxel@...hat.com>,
        David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>
Cc:     linux-arch@...r.kernel.org, Arnd Bergmann <arnd@...nel.org>,
        Albert Ou <aou@...s.berkeley.edu>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
        dri-devel@...ts.freedesktop.org,
        virtualization@...ts.linux-foundation.org,
        Alan Stern <stern@...land.harvard.edu>,
        spice-devel@...ts.freedesktop.org,
        Uwe Kleine-König <u.kleine-koenig@...gutronix.de>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Palmer Dabbelt <palmer@...belt.com>
Subject: Re: [PATCH v4 07/41] drm: handle HAS_IOPORT dependencies

Hi

Am 16.05.23 um 13:00 schrieb Niklas Schnelle:
> In a future patch HAS_IOPORT=n will result in inb()/outb() and friends
> not being declared. We thus need to add HAS_IOPORT as dependency for
> those drivers using them. In the bochs driver there is optional MMIO
> support detected at runtime, warn if this isn't taken when
> HAS_IOPORT is not defined.
> 
> There is also a direct and hard coded use in cirrus.c which according to
> the comment is only necessary during resume.  Let's just skip this as
> for example s390 which doesn't have I/O port support also doesen't
> support suspend/resume.
> 
> Co-developed-by: Arnd Bergmann <arnd@...nel.org>
> Signed-off-by: Arnd Bergmann <arnd@...nel.org>
> Signed-off-by: Niklas Schnelle <schnelle@...ux.ibm.com>
> ---
> Note: The HAS_IOPORT Kconfig option was added in v6.4-rc1 so
>        per-subsystem patches may be applied independently
> 
>   drivers/gpu/drm/qxl/Kconfig   |  1 +
>   drivers/gpu/drm/tiny/bochs.c  | 17 +++++++++++++++++
>   drivers/gpu/drm/tiny/cirrus.c |  2 ++

There are more invocations in gma500. See[1]

[1] 
https://elixir.bootlin.com/linux/v6.3/source/drivers/gpu/drm/gma500/cdv_device.c#L30

>   3 files changed, 20 insertions(+)
> 
> diff --git a/drivers/gpu/drm/qxl/Kconfig b/drivers/gpu/drm/qxl/Kconfig
> index ca3f51c2a8fe..d0e0d440c8d9 100644
> --- a/drivers/gpu/drm/qxl/Kconfig
> +++ b/drivers/gpu/drm/qxl/Kconfig
> @@ -2,6 +2,7 @@
>   config DRM_QXL
>   	tristate "QXL virtual GPU"
>   	depends on DRM && PCI && MMU
> +	depends on HAS_IOPORT
>   	select DRM_KMS_HELPER
>   	select DRM_TTM
>   	select DRM_TTM_HELPER
> diff --git a/drivers/gpu/drm/tiny/bochs.c b/drivers/gpu/drm/tiny/bochs.c
> index d254679a136e..3710339407cc 100644
> --- a/drivers/gpu/drm/tiny/bochs.c
> +++ b/drivers/gpu/drm/tiny/bochs.c
> @@ -2,6 +2,7 @@
>   
>   #include <linux/module.h>
>   #include <linux/pci.h>
> +#include <asm/bug.h>

<linux/bug.h> please.

Best regards
Thomas

>   
>   #include <drm/drm_aperture.h>
>   #include <drm/drm_atomic_helper.h>
> @@ -105,7 +106,9 @@ static void bochs_vga_writeb(struct bochs_device *bochs, u16 ioport, u8 val)
>   
>   		writeb(val, bochs->mmio + offset);
>   	} else {
> +#ifdef CONFIG_HAS_IOPORT
>   		outb(val, ioport);
> +#endif
>   	}
>   }
>   
> @@ -119,7 +122,11 @@ static u8 bochs_vga_readb(struct bochs_device *bochs, u16 ioport)
>   
>   		return readb(bochs->mmio + offset);
>   	} else {
> +#ifdef CONFIG_HAS_IOPORT
>   		return inb(ioport);
> +#else
> +		return 0xff;
> +#endif
>   	}
>   }
>   
> @@ -132,8 +139,12 @@ static u16 bochs_dispi_read(struct bochs_device *bochs, u16 reg)
>   
>   		ret = readw(bochs->mmio + offset);
>   	} else {
> +#ifdef CONFIG_HAS_IOPORT
>   		outw(reg, VBE_DISPI_IOPORT_INDEX);
>   		ret = inw(VBE_DISPI_IOPORT_DATA);
> +#else
> +		ret = 0xffff;
> +#endif
>   	}
>   	return ret;
>   }
> @@ -145,8 +156,10 @@ static void bochs_dispi_write(struct bochs_device *bochs, u16 reg, u16 val)
>   
>   		writew(val, bochs->mmio + offset);
>   	} else {
> +#ifdef CONFIG_HAS_IOPORT
>   		outw(reg, VBE_DISPI_IOPORT_INDEX);
>   		outw(val, VBE_DISPI_IOPORT_DATA);
> +#endif
>   	}
>   }
>   
> @@ -229,6 +242,10 @@ static int bochs_hw_init(struct drm_device *dev)
>   			return -ENOMEM;
>   		}
>   	} else {
> +		if (!IS_ENABLED(CONFIG_HAS_IOPORT)) {
> +			DRM_ERROR("I/O ports are not supported\n");
> +			return -EIO;
> +		}
>   		ioaddr = VBE_DISPI_IOPORT_INDEX;
>   		iosize = 2;
>   		if (!request_region(ioaddr, iosize, "bochs-drm")) {
> diff --git a/drivers/gpu/drm/tiny/cirrus.c b/drivers/gpu/drm/tiny/cirrus.c
> index 594bc472862f..c65fea049bc7 100644
> --- a/drivers/gpu/drm/tiny/cirrus.c
> +++ b/drivers/gpu/drm/tiny/cirrus.c
> @@ -508,8 +508,10 @@ static void cirrus_crtc_helper_atomic_enable(struct drm_crtc *crtc,
>   
>   	cirrus_mode_set(cirrus, &crtc_state->mode);
>   
> +#ifdef CONFIG_HAS_IOPORT
>   	/* Unblank (needed on S3 resume, vgabios doesn't do it then) */
>   	outb(VGA_AR_ENABLE_DISPLAY, VGA_ATT_W);
> +#endif
>   
>   	drm_dev_exit(idx);
>   }

-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstrasse 146, 90461 Nuernberg, Germany
GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman
HRB 36809 (AG Nuernberg)

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