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Message-ID: <64cc9c8f-fff3-4845-bb32-d7f1046ef619@suse.de>
Date: Mon, 21 Oct 2024 09:52:43 +0200
From: Thomas Zimmermann <tzimmermann@...e.de>
To: Niklas Schnelle <schnelle@...ux.ibm.com>, Brian Cain <bcain@...cinc.com>,
Marcel Holtmann <marcel@...tmann.org>,
Luiz Augusto von Dentz <luiz.dentz@...il.com>,
Patrik Jakobsson <patrik.r.jakobsson@...il.com>,
Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
Maxime Ripard <mripard@...nel.org>, David Airlie <airlied@...il.com>,
Simona Vetter <simona@...ll.ch>, Dave Airlie <airlied@...hat.com>,
Gerd Hoffmann <kraxel@...hat.com>, Lucas De Marchi
<lucas.demarchi@...el.com>,
Thomas Hellström <thomas.hellstrom@...ux.intel.com>,
Rodrigo Vivi <rodrigo.vivi@...el.com>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Jiri Slaby <jirislaby@...nel.org>, Arnd Bergmann <arnd@...db.de>,
"Maciej W. Rozycki" <macro@...am.me.uk>, Heiko Carstens <hca@...ux.ibm.com>
Cc: linux-kernel@...r.kernel.org, linux-hexagon@...r.kernel.org,
linux-bluetooth@...r.kernel.org, dri-devel@...ts.freedesktop.org,
virtualization@...ts.linux.dev, spice-devel@...ts.freedesktop.org,
intel-xe@...ts.freedesktop.org, linux-serial@...r.kernel.org,
linux-arch@...r.kernel.org, Arnd Bergmann <arnd@...nel.org>
Subject: Re: [PATCH v8 3/5] drm: handle HAS_IOPORT dependencies
Hi
Am 08.10.24 um 14:39 schrieb Niklas Schnelle:
> In a future patch HAS_IOPORT=n will disable inb()/outb() and friends at
> compile time. 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>
I feel like I reviewed this before, but can't find it.
> ---
> drivers/gpu/drm/gma500/Kconfig | 2 +-
> drivers/gpu/drm/qxl/Kconfig | 1 +
> drivers/gpu/drm/tiny/bochs.c | 17 +++++++++++++++++
> drivers/gpu/drm/tiny/cirrus.c | 2 ++
> drivers/gpu/drm/xe/Kconfig | 2 +-
> 5 files changed, 22 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/gma500/Kconfig b/drivers/gpu/drm/gma500/Kconfig
> index efb4a2dd2f80885cb59c925d09401002278d7d61..23b7c14de5e29238ece939d5822d8a9ffc4675cc 100644
> --- a/drivers/gpu/drm/gma500/Kconfig
> +++ b/drivers/gpu/drm/gma500/Kconfig
> @@ -1,7 +1,7 @@
> # SPDX-License-Identifier: GPL-2.0-only
> config DRM_GMA500
> tristate "Intel GMA500/600/3600/3650 KMS Framebuffer"
> - depends on DRM && PCI && X86 && MMU
> + depends on DRM && PCI && X86 && MMU && HAS_IOPORT
> select DRM_KMS_HELPER
> select FB_IOMEM_HELPERS if DRM_FBDEV_EMULATION
> select I2C
> diff --git a/drivers/gpu/drm/qxl/Kconfig b/drivers/gpu/drm/qxl/Kconfig
> index ca3f51c2a8fe1a383f8a2479f04b5c0b3fb14e44..d0e0d440c8d96564cb7b8ffd2385c44fc43f873d 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
Is there a difference between this style (multiple 'depends on') and the
one used for gma500 (&& && &&)?
> 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 31fc5d839e106ea4d5c8fe42d1bfc3c70291e3fb..0ed78d3d5774778f91de972ac27056938036e722 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 <linux/bug.h>
Alphabetic sorting please.
>
> #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
Could you provide empty defines for the out() interfaces at the top of
the file?
> }
> }
>
> @@ -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
And the in() interfaces could be defined to 0xff[ff].
I assume that you don't want to provide such empty macros in the
kernel's io.h header?
> }
> }
>
> @@ -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;
> + }
It would be nicer to use an "} else if(IOPORT) {" here and put the
"return -EIO" into a trailing else branch.
If you want to add an error message, please don't use DRM_ERROR(). In
this case, dev_err(dev->dev, "...\n") seems appropriate.
Best regards
Thomas
> 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 751326e3d9c374baf72115492aeefff2b73869f0..e31e1df029ab0272c4a1ff0ab3eb026ca679b560 100644
> --- a/drivers/gpu/drm/tiny/cirrus.c
> +++ b/drivers/gpu/drm/tiny/cirrus.c
> @@ -509,8 +509,10 @@ 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);
> }
> diff --git a/drivers/gpu/drm/xe/Kconfig b/drivers/gpu/drm/xe/Kconfig
> index 7bbe46a98ff1f449bc2af30686585a00e9e8af93..116f58774135fc3a9f37d6d72d41340f5c812297 100644
> --- a/drivers/gpu/drm/xe/Kconfig
> +++ b/drivers/gpu/drm/xe/Kconfig
> @@ -49,7 +49,7 @@ config DRM_XE
>
> config DRM_XE_DISPLAY
> bool "Enable display support"
> - depends on DRM_XE && DRM_XE=m
> + depends on DRM_XE && DRM_XE=m && HAS_IOPORT
> select FB_IOMEM_HELPERS
> select I2C
> select I2C_ALGOBIT
>
--
--
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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