Re: [PATCH v5 09/44] drm: handle HAS_IOPORT dependencies

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Am 22.05.23 um 12:50 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.

I think we should consider making cirrus depend on HAS_IOPORT. The driver is only for qemu's cirrus emulation, which IIRC can only be enabled for i586. And it has all been deprecated long ago.

Co-developed-by: Arnd Bergmann <arnd@xxxxxxxxxx>
Signed-off-by: Arnd Bergmann <arnd@xxxxxxxxxx>
Signed-off-by: Niklas Schnelle <schnelle@xxxxxxxxxxxxx>
  drivers/gpu/drm/qxl/Kconfig   |  1 +
  drivers/gpu/drm/tiny/bochs.c  | 17 +++++++++++++++++
  drivers/gpu/drm/tiny/cirrus.c |  2 ++
  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>

Why not <linux/bug.h> ?

#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 {
  		outb(val, ioport);

Would it be feasible to define inb, inw, outb and outw at the top of bochs.c if no HAS_IOPORT has been set? That would avoid the ifdef branching within the code.

@@ -119,7 +122,11 @@ static u8 bochs_vga_readb(struct bochs_device *bochs, u16 ioport) return readb(bochs->mmio + offset);
  	} else {
  		return inb(ioport);
+		return 0xff;
@@ -132,8 +139,12 @@ static u16 bochs_dispi_read(struct bochs_device *bochs, u16 reg) ret = readw(bochs->mmio + offset);
  	} else {
  		outw(reg, VBE_DISPI_IOPORT_INDEX);
  		ret = inw(VBE_DISPI_IOPORT_DATA);
+		ret = 0xffff;
  	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 {
  		outw(reg, VBE_DISPI_IOPORT_INDEX);
  		outw(val, VBE_DISPI_IOPORT_DATA);
@@ -229,6 +242,10 @@ static int bochs_hw_init(struct drm_device *dev)
  			return -ENOMEM;
  	} else {
+			DRM_ERROR("I/O ports are not supported\n");

Use drm_err() here.

Best regards

+			return -EIO;
+		}
  		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) */

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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