fbdev: sm712fb: fix crashes during framebuffer writes by correctly mapping VRAM

[mirror_ubuntu-bionic-kernel.git] / drivers / video / fbdev / sm712fb.c

diff --git a/drivers/video/fbdev/sm712fb.c b/drivers/video/fbdev/sm712fb.c
index e8149f0f47d584a850e34a62d7872a48ac9c66b8..52234c57be02aea56a1caab3e8b37cbdfd383e3d 100644 (file)
--- a/drivers/video/fbdev/sm712fb.c
+++ b/drivers/video/fbdev/sm712fb.c
@@ -1329,6 +1329,11 @@ static int smtc_map_smem(struct smtcfb_info *sfb,
 {
        sfb->fb->fix.smem_start = pci_resource_start(pdev, 0);
 
+       if (sfb->chip_id == 0x720)
+               /* on SM720, the framebuffer starts at the 1 MB offset */
+               sfb->fb->fix.smem_start += 0x00200000;
+
+       /* XXX: is it safe for SM720 on Big-Endian? */
        if (sfb->fb->var.bits_per_pixel == 32)
                sfb->fb->fix.smem_start += big_addr;
 
@@ -1366,12 +1371,45 @@ static inline void sm7xx_init_hw(void)
        outb_p(0x11, 0x3c5);
 }
 
+static u_long sm7xx_vram_probe(struct smtcfb_info *sfb)
+{
+       u8 vram;
+
+       switch (sfb->chip_id) {
+       case 0x710:
+       case 0x712:
+               /*
+                * Assume SM712 graphics chip has 4MB VRAM.
+                *
+                * FIXME: SM712 can have 2MB VRAM, which is used on earlier
+                * laptops, such as IBM Thinkpad 240X. This driver would
+                * probably crash on those machines. If anyone gets one of
+                * those and is willing to help, run "git blame" and send me
+                * an E-mail.
+                */
+               return 0x00400000;
+       case 0x720:
+               outb_p(0x76, 0x3c4);
+               vram = inb_p(0x3c5) >> 6;
+
+               if (vram == 0x00)
+                       return 0x00800000;  /* 8 MB */
+               else if (vram == 0x01)
+                       return 0x01000000;  /* 16 MB */
+               else if (vram == 0x02)
+                       return 0x00400000;  /* illegal, fallback to 4 MB */
+               else if (vram == 0x03)
+                       return 0x00400000;  /* 4 MB */
+       }
+       return 0;  /* unknown hardware */
+}
+
 static int smtcfb_pci_probe(struct pci_dev *pdev,
                            const struct pci_device_id *ent)
 {
        struct smtcfb_info *sfb;
        struct fb_info *info;
-       u_long smem_size = 0x00800000;  /* default 8MB */
+       u_long smem_size;
        int err;
        unsigned long mmio_base;
 
@@ -1428,12 +1466,15 @@ static int smtcfb_pci_probe(struct pci_dev *pdev,
        mmio_base = pci_resource_start(pdev, 0);
        pci_read_config_byte(pdev, PCI_REVISION_ID, &sfb->chip_rev_id);
 
+       smem_size = sm7xx_vram_probe(sfb);
+       dev_info(&pdev->dev, "%lu MiB of VRAM detected.\n",
+                                       smem_size / 1048576);
+
        switch (sfb->chip_id) {
        case 0x710:
        case 0x712:
                sfb->fb->fix.mmio_start = mmio_base + 0x00400000;
                sfb->fb->fix.mmio_len = 0x00400000;
-               smem_size = SM712_VIDEOMEMORYSIZE;
                sfb->lfb = ioremap(mmio_base, mmio_addr);
                if (!sfb->lfb) {
                        dev_err(&pdev->dev,
@@ -1465,8 +1506,7 @@ static int smtcfb_pci_probe(struct pci_dev *pdev,
        case 0x720:
                sfb->fb->fix.mmio_start = mmio_base;
                sfb->fb->fix.mmio_len = 0x00200000;
-               smem_size = SM722_VIDEOMEMORYSIZE;
-               sfb->dp_regs = ioremap(mmio_base, 0x00a00000);
+               sfb->dp_regs = ioremap(mmio_base, 0x00200000 + smem_size);
                sfb->lfb = sfb->dp_regs + 0x00200000;
                sfb->mmio = (smtc_regbaseaddress =
                    sfb->dp_regs + 0x000c0000);