Daniel Mack <zonque@xxxxxxxxx> writes:
> This patch makes the edma driver resume correctly after suspend. Tested
> on an AM33xx platform with cyclic audio streams.
Please add a little more detail abou why the EDMA loses its context
across suspend/resume (e.g. which power domain(s) its in, and why they
lose context across suspend/resume.
Also, is a full context save necessary every time? What if no channels
are in use? Also, is a full restore necessary every time? Are there
cases where the domain doesn't lose context and a restore would not be
necessary? Often this can be checked by reading register(s) that has a
known power-on reset value.
> The code was shamelessly taken from an ancient BSP tree.
>
> Signed-off-by: Daniel Mack <zonque@xxxxxxxxx>
[...]
> +static int edma_pm_suspend(struct device *dev)
> +{
> + int i, j;
> +
> + pm_runtime_get_sync(dev);
> +
> + for (i = 0; i < arch_num_cc; i++) {
> + struct edma *ecc = edma_cc[i];
> +
> + /* backup channel data */
> + for (j = 0; j < ecc->num_channels; j++)
> + ecc->context.ch_map[j] =
> + edma_read_array(i, EDMA_DCHMAP, j);
> +
> + /* backup DMA Queue Number */
> + for (j = 0; j < 8; j++)
> + ecc->context.que_num[j] =
> + edma_read_array(i, EDMA_DMAQNUM, j);
> +
> + /* backup DMA shadow Event Set data */
> + ecc->context.sh_esr = edma_shadow0_read_array(i, SH_ESR, 0);
> + ecc->context.sh_esrh = edma_shadow0_read_array(i, SH_ESR, 1);
> +
> + /* backup DMA Shadow Event Enable Set data */
> + ecc->context.sh_eesr =
> + edma_shadow0_read_array(i, SH_EER, 0);
> + ecc->context.sh_eesrh =
> + edma_shadow0_read_array(i, SH_EER, 1);
> +
> + /* backup DMA Shadow Interrupt Enable Set data */
> + ecc->context.sh_iesr =
> + edma_shadow0_read_array(i, SH_IER, 0);
> + ecc->context.sh_iesrh =
> + edma_shadow0_read_array(i, SH_IER, 1);
> +
> + ecc->context.que_tc_map = edma_read(i, EDMA_QUETCMAP);
> +
> + /* backup DMA Queue Priority data */
> + ecc->context.que_pri = edma_read(i, EDMA_QUEPRI);
> +
> + /* backup paramset */
> + for (j = 0; j < ecc->num_slots; j++)
> + memcpy_fromio(&ecc->context.prm_set[j],
> + edmacc_regs_base[i] + PARM_OFFSET(j),
> + PARM_SIZE);
> + }
The actual context save doesn't belong here, it belongs in the
->runtime_suspend callback(), and conversly the context restore belongs
in the ->runtime_resume() callback.
> + pm_runtime_put_sync(dev);
> +
> + return 0;
> +}
Kevin
--
To unsubscribe from this list: send the line "unsubscribe linux-omap" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
