Re: [PATCH v4 38/41] video: handle HAS_IOPORT dependencies
From: Niklas Schnelle
Date: Wed May 17 2023 - 08:41:51 EST
On Tue, 2023-05-16 at 19:21 +0200, Thomas Zimmermann wrote:
> 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 and guard inline code in headers.
> >
> > Co-developed-by: Arnd Bergmann <arnd@xxxxxxxxxx>
> > Signed-off-by: Arnd Bergmann <arnd@xxxxxxxxxx>
> > Signed-off-by: Niklas Schnelle <schnelle@xxxxxxxxxxxxx>
> > ---
> > Note: The HAS_IOPORT Kconfig option was added in v6.4-rc1 so
> > per-subsystem patches may be applied independently
> >
> > drivers/video/console/Kconfig | 1 +
> > drivers/video/fbdev/Kconfig | 21 +++++++++++----------
> > include/video/vga.h | 8 ++++++++
>
> Those are 3 different things. It might be preferable to not handle them
> under the video/ umbrella.
>
> > 3 files changed, 20 insertions(+), 10 deletions(-)
> >
> > diff --git a/drivers/video/console/Kconfig b/drivers/video/console/Kconfig
> > index 22cea5082ac4..64974eaa3ac5 100644
> > --- a/drivers/video/console/Kconfig
> > +++ b/drivers/video/console/Kconfig
> > @@ -10,6 +10,7 @@ config VGA_CONSOLE
> > depends on !4xx && !PPC_8xx && !SPARC && !M68K && !PARISC && !SUPERH && \
> > (!ARM || ARCH_FOOTBRIDGE || ARCH_INTEGRATOR || ARCH_NETWINDER) && \
> > !ARM64 && !ARC && !MICROBLAZE && !OPENRISC && !S390 && !UML
> > + depends on HAS_IOPORT
> > select APERTURE_HELPERS if (DRM || FB || VFIO_PCI_CORE)
> > default y
> > help
> > diff --git a/drivers/video/fbdev/Kconfig b/drivers/video/fbdev/Kconfig
> > index 96e91570cdd3..a56c57dd839b 100644
> > --- a/drivers/video/fbdev/Kconfig
> > +++ b/drivers/video/fbdev/Kconfig
> > @@ -335,7 +335,7 @@ config FB_IMX
> >
> > config FB_CYBER2000
> > tristate "CyberPro 2000/2010/5000 support"
> > - depends on FB && PCI && (BROKEN || !SPARC64)
> > + depends on FB && PCI && HAS_IOPORT && (BROKEN || !SPARC64)
> > select FB_CFB_FILLRECT
> > select FB_CFB_COPYAREA
> > select FB_CFB_IMAGEBLIT
> > @@ -429,6 +429,7 @@ config FB_FM2
> > config FB_ARC
> > tristate "Arc Monochrome LCD board support"
> > depends on FB && (X86 || COMPILE_TEST)
> > + depends on HAS_IOPORT
> > select FB_SYS_FILLRECT
> > select FB_SYS_COPYAREA
> > select FB_SYS_IMAGEBLIT
> > @@ -1332,7 +1333,7 @@ config FB_ATY_BACKLIGHT
> >
> > config FB_S3
> > tristate "S3 Trio/Virge support"
> > - depends on FB && PCI
> > + depends on FB && PCI && HAS_IOPORT
> > select FB_CFB_FILLRECT
> > select FB_CFB_COPYAREA
> > select FB_CFB_IMAGEBLIT
> > @@ -1393,7 +1394,7 @@ config FB_SAVAGE_ACCEL
> >
> > config FB_SIS
> > tristate "SiS/XGI display support"
> > - depends on FB && PCI
> > + depends on FB && PCI && HAS_IOPORT
> > select FB_CFB_FILLRECT
> > select FB_CFB_COPYAREA
> > select FB_CFB_IMAGEBLIT
> > @@ -1424,7 +1425,7 @@ config FB_SIS_315
> >
> > config FB_VIA
> > tristate "VIA UniChrome (Pro) and Chrome9 display support"
> > - depends on FB && PCI && GPIOLIB && I2C && (X86 || COMPILE_TEST)
> > + depends on FB && PCI && GPIOLIB && I2C && HAS_IOPORT && (X86 || COMPILE_TEST)
> > select FB_CFB_FILLRECT
> > select FB_CFB_COPYAREA
> > select FB_CFB_IMAGEBLIT
> > @@ -1463,7 +1464,7 @@ endif
> >
> > config FB_NEOMAGIC
> > tristate "NeoMagic display support"
> > - depends on FB && PCI
> > + depends on FB && PCI && HAS_IOPORT
> > select FB_MODE_HELPERS
> > select FB_CFB_FILLRECT
> > select FB_CFB_COPYAREA
> > @@ -1493,7 +1494,7 @@ config FB_KYRO
> >
> > config FB_3DFX
> > tristate "3Dfx Banshee/Voodoo3/Voodoo5 display support"
> > - depends on FB && PCI
> > + depends on FB && PCI && HAS_IOPORT
> > select FB_CFB_IMAGEBLIT
> > select FB_CFB_FILLRECT
> > select FB_CFB_COPYAREA
> > @@ -1543,7 +1544,7 @@ config FB_VOODOO1
> >
> > config FB_VT8623
> > tristate "VIA VT8623 support"
> > - depends on FB && PCI
> > + depends on FB && PCI && HAS_IOPORT
> > select FB_CFB_FILLRECT
> > select FB_CFB_COPYAREA
> > select FB_CFB_IMAGEBLIT
> > @@ -1558,7 +1559,7 @@ config FB_VT8623
> >
> > config FB_TRIDENT
> > tristate "Trident/CyberXXX/CyberBlade support"
> > - depends on FB && PCI
> > + depends on FB && PCI && HAS_IOPORT
> > select FB_CFB_FILLRECT
> > select FB_CFB_COPYAREA
> > select FB_CFB_IMAGEBLIT
> > @@ -1581,7 +1582,7 @@ config FB_TRIDENT
> >
> > config FB_ARK
> > tristate "ARK 2000PV support"
> > - depends on FB && PCI
> > + depends on FB && PCI && HAS_IOPORT
> > select FB_CFB_FILLRECT
> > select FB_CFB_COPYAREA
> > select FB_CFB_IMAGEBLIT
> > @@ -2195,7 +2196,7 @@ config FB_SSD1307
> >
> > config FB_SM712
> > tristate "Silicon Motion SM712 framebuffer support"
> > - depends on FB && PCI
> > + depends on FB && PCI && HAS_IOPORT
> > select FB_CFB_FILLRECT
> > select FB_CFB_COPYAREA
> > select FB_CFB_IMAGEBLIT
> > diff --git a/include/video/vga.h b/include/video/vga.h
> > index 947c0abd04ef..f4b806b85c86 100644
> > --- a/include/video/vga.h
> > +++ b/include/video/vga.h
> > @@ -203,18 +203,26 @@ extern int restore_vga(struct vgastate *state);
> >
> > static inline unsigned char vga_io_r (unsigned short port)
> > {
> > +#ifdef CONFIG_HAS_IOPORT
> > return inb_p(port);
> > +#else
> > + return 0xff;
> > +#endif
> > }
> >
> > static inline void vga_io_w (unsigned short port, unsigned char val)
> > {
> > +#ifdef CONFIG_HAS_IOPORT
> > outb_p(val, port);
> > +#endif
> > }
> >
> > static inline void vga_io_w_fast (unsigned short port, unsigned char reg,
> > unsigned char val)
> > {
> > +#ifdef CONFIG_HAS_IOPORT
> > outw(VGA_OUT16VAL (val, reg), port);
> > +#endif
> > }
>
> It feels wrong that these helpers silently do nothing. I'd enclose them
> in CONFIG_HAS_IOPORT entirely. The drivers that use them unconditionally
> would then fail to build.
>
> Best regards
> Thomas
Ok yeah, I was looking at the call sites like vga_w_fast() that use
either an HAS_IOPORT dependent function or a writew() based one and so
if I #ifdef the regbase != NULL check we could end up with a NULL
derference but I guess that is kind of what we want since clearly
something is wrong if the driver tries to do I/O port access despite it
not being available.
Thanks,
Niklas