EHCI real mode driver PORTSC issue

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Jonatan44
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EHCI real mode driver PORTSC issue

Post by Jonatan44 »

hi everyone,
I'm working on ehci driver for real mode platform, when i look for connected devices the default value of the disconnected port (portsc[n]) is 0x1000 instead of 0x2000 or 0x3000 as specified in ehci specs, what can cause the portsc[n] to change it's default value?

thanks!
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jal
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Re: EHCI real mode driver PORTSC issue

Post by jal »

Jonatan44 wrote:I'm working on ehci driver for real mode platform, when i look for connected devices the default value of the disconnected port (portsc[n]) is 0x1000 instead of 0x2000 or 0x3000 as specified in ehci specs, what can cause the portsc[n] to change it's default value?
BIOS?


JAL
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pcmattman
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Re: EHCI real mode driver PORTSC issue

Post by pcmattman »

You should do a BIOS handoff and then an EHCI reset before reading any of the port status registers. After a proper handoff/reset you should see the proper "default value" for ports.

Also note that on some controllers you need to power up the port before it reports anything useful such as device presence or the enabled state.
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