| Message ID | 4F30EFBA.3090400@esd.eu |
|---|---|
| State | Accepted |
| Commit | 61698fd563bb3747079c079558d590e45d130552 |
| Delegated to: | Stefano Babic |
| Headers | show |
> This patch fixes booting i.MX28 CPUs via USB download. > In this mode the CPU's bootrom implements a USB HID device that > accepts a bootstream. > > When downloading the bootstream via USB, first the SPL code is > received and executed. Then the u-boot image is received and > called. > > The USB bootmode is interrupt driven. > > This patch fixes two things: > > 1) The ARM's fast interrupt mode is disabled when the SPL code > has been run. So save and restore the CPSR register. > > 2) Save and restore c1 control register: the exception vector > location needs to be set back to bootrom space to make the USB > interrupts work again. The SPL code needs to change this > option for the ram size probing. > > Signed-off-by: Matthias Fuchs <matthias.fuchs@esd.eu> > --- > changes in v2: > - store old SPSR on stack instead of jiggling around with some bits > - remove #ifndef CONFIG_SKIP_LOWLEVEL_INIT > changes in v3: > - also store C1 register on stack > > arch/arm/cpu/arm926ejs/mx28/start.S | 21 ++++++++++++++++++++- > 1 files changed, 20 insertions(+), 1 deletions(-) > > diff --git a/arch/arm/cpu/arm926ejs/mx28/start.S > b/arch/arm/cpu/arm926ejs/mx28/start.S index 2cd4d73..e572b78 100644 > --- a/arch/arm/cpu/arm926ejs/mx28/start.S > +++ b/arch/arm/cpu/arm926ejs/mx28/start.S > @@ -167,10 +167,15 @@ _reset: > */ > push {r0-r12,r14} > > + /* save control register c1 */ > + mrc p15, 0, r0, c1, c0, 0 > + push {r0} > + > /* > - * set the cpu to SVC32 mode > + * set the cpu to SVC32 mode and store old CPSR register content > */ > mrs r0,cpsr > + push {r0} > bic r0,r0,#0x1f > orr r0,r0,#0xd3 > msr cpsr,r0 > @@ -185,6 +190,20 @@ _reset: > > bl board_init_ll > > + /* > + * restore bootrom's cpu mode (especially FIQ) > + */ > + pop {r0} > + msr cpsr,r0 > + > + /* > + * restore c1 register > + * (especially set exception vector location back to > + * bootrom space which is required by bootrom for USB boot) > + */ > + pop {r0} > + mcr p15, 0, r0, c1, c0, 0 > + > pop {r0-r12,r14} > bx lr Yep, looks fine. Stefano, can you apply? Or shall I start hand-picking these mx28 patches and then send you a pullrq? Acked-by: Marek Vasut <marek.vasut@gmail.com>
On 07/02/2012 17:54, Marek Vasut wrote: >> This patch fixes booting i.MX28 CPUs via USB download. >> In this mode the CPU's bootrom implements a USB HID device that >> accepts a bootstream. >> >> When downloading the bootstream via USB, first the SPL code is >> received and executed. Then the u-boot image is received and >> called. >> >> The USB bootmode is interrupt driven. >> >> This patch fixes two things: >> >> 1) The ARM's fast interrupt mode is disabled when the SPL code >> has been run. So save and restore the CPSR register. >> >> 2) Save and restore c1 control register: the exception vector >> location needs to be set back to bootrom space to make the USB >> interrupts work again. The SPL code needs to change this >> option for the ram size probing. >> >> Signed-off-by: Matthias Fuchs <matthias.fuchs@esd.eu> >> --- >> changes in v2: >> - store old SPSR on stack instead of jiggling around with some bits >> - remove #ifndef CONFIG_SKIP_LOWLEVEL_INIT >> changes in v3: >> - also store C1 register on stack >> >> arch/arm/cpu/arm926ejs/mx28/start.S | 21 ++++++++++++++++++++- >> 1 files changed, 20 insertions(+), 1 deletions(-) >> >> diff --git a/arch/arm/cpu/arm926ejs/mx28/start.S >> b/arch/arm/cpu/arm926ejs/mx28/start.S index 2cd4d73..e572b78 100644 >> --- a/arch/arm/cpu/arm926ejs/mx28/start.S >> +++ b/arch/arm/cpu/arm926ejs/mx28/start.S >> @@ -167,10 +167,15 @@ _reset: >> */ >> push {r0-r12,r14} >> >> + /* save control register c1 */ >> + mrc p15, 0, r0, c1, c0, 0 >> + push {r0} >> + >> /* >> - * set the cpu to SVC32 mode >> + * set the cpu to SVC32 mode and store old CPSR register content >> */ >> mrs r0,cpsr >> + push {r0} >> bic r0,r0,#0x1f >> orr r0,r0,#0xd3 >> msr cpsr,r0 >> @@ -185,6 +190,20 @@ _reset: >> >> bl board_init_ll >> >> + /* >> + * restore bootrom's cpu mode (especially FIQ) >> + */ >> + pop {r0} >> + msr cpsr,r0 >> + >> + /* >> + * restore c1 register >> + * (especially set exception vector location back to >> + * bootrom space which is required by bootrom for USB boot) >> + */ >> + pop {r0} >> + mcr p15, 0, r0, c1, c0, 0 >> + >> pop {r0-r12,r14} >> bx lr > > Yep, looks fine. Stefano, can you apply? Or shall I start hand-picking these > mx28 patches and then send you a pullrq? No problem, I will apply it to u-boot-imx Stefano
On 07/02/2012 10:32, Matthias Fuchs wrote: > This patch fixes booting i.MX28 CPUs via USB download. > In this mode the CPU's bootrom implements a USB HID device that > accepts a bootstream. > > When downloading the bootstream via USB, first the SPL code is > received and executed. Then the u-boot image is received and > called. > > The USB bootmode is interrupt driven. > > This patch fixes two things: > > 1) The ARM's fast interrupt mode is disabled when the SPL code > has been run. So save and restore the CPSR register. > > 2) Save and restore c1 control register: the exception vector > location needs to be set back to bootrom space to make the USB > interrupts work again. The SPL code needs to change this > option for the ram size probing. > > Signed-off-by: Matthias Fuchs <matthias.fuchs@esd.eu> Applied to u-boot-imx, thanks Best regards, Stefano Babic
diff --git a/arch/arm/cpu/arm926ejs/mx28/start.S b/arch/arm/cpu/arm926ejs/mx28/start.S index 2cd4d73..e572b78 100644 --- a/arch/arm/cpu/arm926ejs/mx28/start.S +++ b/arch/arm/cpu/arm926ejs/mx28/start.S @@ -167,10 +167,15 @@ _reset: */ push {r0-r12,r14} + /* save control register c1 */ + mrc p15, 0, r0, c1, c0, 0 + push {r0} + /* - * set the cpu to SVC32 mode + * set the cpu to SVC32 mode and store old CPSR register content */ mrs r0,cpsr + push {r0} bic r0,r0,#0x1f orr r0,r0,#0xd3 msr cpsr,r0 @@ -185,6 +190,20 @@ _reset: bl board_init_ll + /* + * restore bootrom's cpu mode (especially FIQ) + */ + pop {r0} + msr cpsr,r0 + + /* + * restore c1 register + * (especially set exception vector location back to + * bootrom space which is required by bootrom for USB boot) + */ + pop {r0} + mcr p15, 0, r0, c1, c0, 0 + pop {r0-r12,r14} bx lr
This patch fixes booting i.MX28 CPUs via USB download. In this mode the CPU's bootrom implements a USB HID device that accepts a bootstream. When downloading the bootstream via USB, first the SPL code is received and executed. Then the u-boot image is received and called. The USB bootmode is interrupt driven. This patch fixes two things: 1) The ARM's fast interrupt mode is disabled when the SPL code has been run. So save and restore the CPSR register. 2) Save and restore c1 control register: the exception vector location needs to be set back to bootrom space to make the USB interrupts work again. The SPL code needs to change this option for the ram size probing. Signed-off-by: Matthias Fuchs <matthias.fuchs@esd.eu> --- changes in v2: - store old SPSR on stack instead of jiggling around with some bits - remove #ifndef CONFIG_SKIP_LOWLEVEL_INIT changes in v3: - also store C1 register on stack arch/arm/cpu/arm926ejs/mx28/start.S | 21 ++++++++++++++++++++- 1 files changed, 20 insertions(+), 1 deletions(-)