xfnw/plan9fox
1
0
Fork 0
Code Issues Pull requests Projects Releases Wiki Activity

imx8: qos magic to avoid interference between pcie and lcdif

Browse source 
when writing to the nvme ssd, the screen can glitch out.

found this in linux lcdif driver (mxcfb) that appears to
resolve the issue.

the QoSc registers are all completely undocumented tho :-(
This commit is contained in:
cinap_lenrek 2022-07-03 16:13:19 +00:00
parent 940e3165d3
commit c5cf9b3e26
1 changed files with 30 additions and 0 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

30
sys/src/9/imx8/pciimx.c
View file

@ -410,6 +410,34 @@ pcicfginit(void)
rootinit(&ctlrs[1]); rootinit(&ctlrs[1]);
} }
/* undocumented magic to avoid interference between lcdif and pcie */
static void
qosmagic(void)
{
static u32int *qosc = (u32int*)(VIRTIO + 0x7f0000);
/* unlock */
qosc[0x0000/4] = 0x0;
qosc[0x0000/4] = 0x1;
qosc[0x0060/4] = 0x0;
/* pci1 */
qosc[0x1000/4] = 0x0;
qosc[0x1000/4] = 0x1;
qosc[0x1050/4] = 0x01010100;
qosc[0x1060/4] = 0x01010100;
qosc[0x1070/4] = 0x01010100;
qosc[0x1000/4] = 0x1;
/* pcie2 */
qosc[0x2000/4] = 0x0;
qosc[0x2000/4] = 0x1;
qosc[0x2050/4] = 0x01010100;
qosc[0x2060/4] = 0x01010100;
qosc[0x2070/4] = 0x01010100;
qosc[0x2000/4] = 0x1;
}
enum { enum {
SRC_PCIEPHY_RCR = 0x2C/4, SRC_PCIEPHY_RCR = 0x2C/4,
SRC_PCIE2_RCR = 0x48/4, SRC_PCIE2_RCR = 0x48/4,
@ -494,4 +522,6 @@ pciimxlink(void)
resetc[SRC_PCIE2_RCR] &= ~(PCIE_BTN | PCIE_G_RST); resetc[SRC_PCIE2_RCR] &= ~(PCIE_BTN | PCIE_G_RST);
pcicfginit(); pcicfginit();
qosmagic();
} }