On 15.11.2022 15:46:28, Frieder Schrempf wrote:
> > diff --git a/drivers/spi/spi-imx.c b/drivers/spi/spi-imx.c
> > index 30d82cc7300b..76021b9bb445 100644
> > --- a/drivers/spi/spi-imx.c
> > +++ b/drivers/spi/spi-imx.c
> > @@ -1270,9 +1270,22 @@ static int spi_imx_setupxfer(struct spi_device *spi,
> > spi_imx->dynamic_burst = 0;
> > }
> >
> > - if (spi_imx_can_dma(spi_imx->controller, spi, t))
> > - spi_imx->usedma = true;
> > - else
> > + if (spi_imx_can_dma(spi_imx->controller, spi, t)) {
> > + unsigned long hz_per_byte, byte_limit;
> > +
> > + /*
> > + * Calculate the estimated time in us the transfer runs. Find
> > + * the number of Hz per byte per polling limit.
> > + */
> > + hz_per_byte = polling_limit_us ? ((8 + 4) * USEC_PER_SEC) / polling_limit_us : 0;
> > + byte_limit = hz_per_byte ? t->effective_speed_hz / hz_per_byte : 1;
> > +
> > + /* run in polling mode for short transfers */
> > + if (t->len < byte_limit)
> > + spi_imx->usedma = false;
> > + else
> > + spi_imx->usedma = true;
> > + } else
> > spi_imx->usedma = false;
> >
> > spi_imx->rx_only = ((t->tx_buf == NULL)
> > @@ -1597,8 +1610,8 @@ static int spi_imx_transfer_one(struct spi_controller *controller,
> > struct spi_imx_data *spi_imx = spi_controller_get_devdata(spi->controller);
> > unsigned long hz_per_byte, byte_limit;
> >
> > - spi_imx_setupxfer(spi, transfer);
> > transfer->effective_speed_hz = spi_imx->spi_bus_clk;
> > + spi_imx_setupxfer(spi, transfer);
> >
> > /* flush rxfifo before transfer */
> > while (spi_imx->devtype_data->rx_available(spi_imx))
> >
>
> Thanks for the patch, but unfortunately this doesn't help. I did some
> more debugging and it looks like there are two problems.
Can you try this one?
diff --git a/drivers/spi/spi-imx.c b/drivers/spi/spi-imx.c
index 30d82cc7300b..d45da1d0ac1d 100644
--- a/drivers/spi/spi-imx.c
+++ b/drivers/spi/spi-imx.c
@@ -1607,6 +1607,13 @@ static int spi_imx_transfer_one(struct spi_controller *controller,
if (spi_imx->slave_mode)
return spi_imx_pio_transfer_slave(spi, transfer);
+ /*
+ * If we decided in spi_imx_can_dma() that we want to do a DMA
+ * transfer, the message has already been mapped, so we have
+ * to do the DMA transfer now.
+ */
+ if (spi_imx->usedma)
+ return spi_imx_dma_transfer(spi_imx, transfer);
/*
* Calculate the estimated time in us the transfer runs. Find
* the number of Hz per byte per polling limit.
@@ -1618,9 +1625,6 @@ static int spi_imx_transfer_one(struct spi_controller *controller,
if (transfer->len < byte_limit)
return spi_imx_poll_transfer(spi, transfer);
- if (spi_imx->usedma)
- return spi_imx_dma_transfer(spi_imx, transfer);
-
return spi_imx_pio_transfer(spi, transfer);
}
The problem is: we decide on DMA in spi_imx_can_dma() the SPI frameworks
maps the message, and then calls spi_imx_transfer_one(). We cannot
operate with the CPU in the memory mapped to the DMA engine.
This should fix the problem without any additional patches.
regards,
Marc
--
Pengutronix e.K. | Marc Kleine-Budde |
Embedded Linux | https://www.pengutronix.de |
Vertretung West/Dortmund | Phone: +49-231-2826-924 |
Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
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