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Date: Sun, 15 Oct 2006 11:04:58 +0200
From: usleepless@gmail.com
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Subject: Fwd: Removing Giant from a driver
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---------- Forwarded message ----------
From: usleepless@gmail.com <usleepless@gmail.com>
Date: Oct 14, 2006 10:32 PM
Subject: Removing Giant from a driver
To: freebsd-questions@freebsd.org


Hi All,

i have been tweaking the pvr250 driver to support pvr150s/500s. now i
want to remove Giant from the code.

problem is, i am not sure what to do. i have created a mutex which
replaces the spltty and splx calls. but this crashes my box :-)

the original code looks like this:
        /*
         * Allocate a DMA tag for the scatter / gather list.
         */
        error = bus_dma_tag_create(sc->parent_dmat, 1, 0,
                                   BUS_SPACE_MAXADDR_32BIT,
                                   BUS_SPACE_MAXADDR, NULL, NULL,
                                   CXM_SG_BUFFERS
                                   * sizeof(struct cxm_sg_entry), 1,
                                   BUS_SPACE_MAXSIZE_32BIT, 0,
#if __FreeBSD_version >= 501102
                                   busdma_lock_mutex, &Giant,
#endif
                                   &sc->enc_sg.dmat);

what should it look like?

and how will i prevent the interrupt routine from interfering with
userland operations? can i place a "mtx_lock()" call in the interrupt
routine?

is there a howto somewhere?

regards,

usleep