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m68k: mac: Fix IOP status/control register writes 

[ Upstream commit 931fc82a6a ]

When writing values to the IOP status/control register make sure those
values do not have any extraneous bits that will clear interrupt flags.

To place the SCC IOP into bypass mode would be desirable but this is not
achieved by writing IOP_DMAINACTIVE | IOP_RUN | IOP_AUTOINC | IOP_BYPASS
to the control register. Drop this ineffective register write.

Remove the flawed and unused iop_bypass() function. Make use of the
unused iop_stop() function.

Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Tested-by: Stan Johnson <userm57@yahoo.com>
Cc: Joshua Thompson <funaho@jurai.org>
Link: https://lore.kernel.org/r/09bcb7359a1719a18b551ee515da3c4c3cf709e6.1590880333.git.fthain@telegraphics.com.au
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
5.4-rM2-2.2.x-imx-squashed
Finn Thain 2020-05-31 09:12:13 +10:00 committed by Greg Kroah-Hartman
parent b8ad79dde6
commit 78448034fa
1 changed files with 3 additions and 9 deletions
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12
arch/m68k/mac/iop.c
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@ -183,7 +183,7 @@ static __inline__ void iop_writeb(volatile struct mac_iop *iop, __u16 addr, __u8
static __inline__ void iop_stop(volatile struct mac_iop *iop)
{
iop->status_ctrl &= ~IOP_RUN;
iop->status_ctrl = IOP_AUTOINC;
}
static __inline__ void iop_start(volatile struct mac_iop *iop)
@ -191,14 +191,9 @@ static __inline__ void iop_start(volatile struct mac_iop *iop)
iop->status_ctrl = IOP_RUN | IOP_AUTOINC;
}
static __inline__ void iop_bypass(volatile struct mac_iop *iop)
{
iop->status_ctrl |= IOP_BYPASS;
}
static __inline__ void iop_interrupt(volatile struct mac_iop *iop)
{
iop->status_ctrl |= IOP_IRQ;
iop->status_ctrl = IOP_IRQ | IOP_RUN | IOP_AUTOINC;
}
static int iop_alive(volatile struct mac_iop *iop)
@ -244,7 +239,6 @@ void __init iop_preinit(void)
} else {
iop_base[IOP_NUM_SCC] = (struct mac_iop *) SCC_IOP_BASE_QUADRA;
}
iop_base[IOP_NUM_SCC]->status_ctrl = 0x87;
iop_scc_present = 1;
} else {
iop_base[IOP_NUM_SCC] = NULL;
@ -256,7 +250,7 @@ void __init iop_preinit(void)
} else {
iop_base[IOP_NUM_ISM] = (struct mac_iop *) ISM_IOP_BASE_QUADRA;
}
iop_base[IOP_NUM_ISM]->status_ctrl = 0;
iop_stop(iop_base[IOP_NUM_ISM]);
iop_ism_present = 1;
} else {
iop_base[IOP_NUM_ISM] = NULL;