RE: [PATCH v10 05/12] dmaengine: dma: imx-sdma: add fw_loaded and is_ram_script

[Robin Gong <yibin.gong@nxp.com>]

> On 2020/07/23 17:04 Frieder Schrempf <frieder.schrempf@kontron.de>
> wrote:
> > Hi Robin,
> >
> > On 30.06.20 15:31, Robin Gong wrote:
> > > Add 'fw_loaded' and 'is_ram_script' to check if the script used by
> > > channel is ram script and it's loaded or not, so that could prevent
> > > meaningless following malloc dma descriptor and bd allocate in
> > > sdma_transfer_init(), otherwise memory may be consumed out
> > > potentially without free in case that spi fallback into pio while
> > > dma transfer failed by sdma firmware not ready(next ERR009165 patch
> > > depends on sdma
> > RAM scripts/firmware).
> > >
> > > Signed-off-by: Robin Gong <yibin.gong@nxp.com>
> > > Acked-By: Vinod Koul <vkoul@kernel.org>
> > > ---
> > >   drivers/dma/imx-sdma.c | 13 +++++++++++++
> > >   1 file changed, 13 insertions(+)
> > >
> > > diff --git a/drivers/dma/imx-sdma.c b/drivers/dma/imx-sdma.c index
> > > 5411e01e..ce1c83e 100644
> > > --- a/drivers/dma/imx-sdma.c
> > > +++ b/drivers/dma/imx-sdma.c
> > > @@ -379,6 +379,7 @@ struct sdma_channel {
> > >   	enum dma_status			status;
> > >   	struct imx_dma_data		data;
> > >   	struct work_struct		terminate_worker;
> > > +	bool				is_ram_script;
> > >   };
> > >
> > >   #define IMX_DMA_SG_LOOP		BIT(0)
> > > @@ -443,6 +444,7 @@ struct sdma_engine {
> > >   	struct sdma_buffer_descriptor	*bd0;
> > >   	/* clock ratio for AHB:SDMA core. 1:1 is 1, 2:1 is 0*/
> > >   	bool				clk_ratio;
> > > +	bool                            fw_loaded;
> > >   };
> > >
> > >   static int sdma_config_write(struct dma_chan *chan, @@ -929,6
> > > +931,7 @@ static void sdma_get_pc(struct sdma_channel *sdmac,
> > >   	case IMX_DMATYPE_SSI_DUAL:
> > >   		per_2_emi = sdma->script_addrs->ssish_2_mcu_addr;
> > >   		emi_2_per = sdma->script_addrs->mcu_2_ssish_addr;
> > > +		sdmac->is_ram_script = true;
> > >   		break;
> > >   	case IMX_DMATYPE_SSI_SP:
> > >   	case IMX_DMATYPE_MMC:
> > > @@ -943,6 +946,7 @@ static void sdma_get_pc(struct sdma_channel
> > *sdmac,
> > >   		per_2_emi = sdma->script_addrs->asrc_2_mcu_addr;
> > >   		emi_2_per = sdma->script_addrs->asrc_2_mcu_addr;
> > >   		per_2_per = sdma->script_addrs->per_2_per_addr;
> > > +		sdmac->is_ram_script = true;
> > >   		break;
> > >   	case IMX_DMATYPE_ASRC_SP:
> > >   		per_2_emi = sdma->script_addrs->shp_2_mcu_addr;
> > > @@ -1339,6 +1343,11 @@ static struct sdma_desc
> > *sdma_transfer_init(struct sdma_channel *sdmac,
> > >   {
> > >   	struct sdma_desc *desc;
> > >
> > > +	if (!sdmac->sdma->fw_loaded && sdmac->is_ram_script) {
> > > +		dev_err(sdmac->sdma->dev, "sdma firmware not ready!\n");
> > > +		goto err_out;
> > > +	}
> >
> > I tried your v10 patches on next-20200722 with i.MX8MM and it mostly
> > seems to work fine.
> >
> > When I tried first, I had the imx-sdma driver compiled into the
> > kernel, so it didn't load the firmware and fell back to the ROM scripts.
> > With this, SPI transactions work just fine, but I got the above error
> > message printed continuously when sending data in SPI3 via spidev.
> That's caused by you didn't load ram firmware as this patch set described.
> Please follow below steps to load firmware manually if you don't want to use
> NXP official Yocto release package:
> 
> 1. Get sdma firmware from below linux-firmware and copy it to your local
> rootfs /lib/firmware/imx/sdma.
> https://git.kernel.org/pub/scm/linux/kernel/git/firmware/linux-firmware.git/t
> ree/imx/sdma
> 2. Load firmware manually:
>         echo 1 > /sys/$DEVPATH/loading
>         cat $MY_FW_DIR/$FIRMWARE > /sys/$DEVPATH/data
>         echo 0 > /sys/$DEVPATH/loading
> Please refer to Documentation/driver-api/firmware/fallback-mechanisms.rst
> and load the firmware in 60s (firmware fallback loading timeout) from kernel
> boot up.
> 
> >
> > When I build imx-sdma as a module, the firmware is loaded correctly
> > and everything works as expected.
> I guess that's not related with sdma building as module. If sdma build as
> module, spi will fall to pio mode at spi-imx driver probe phase so that the
> above warning log never to be walked. Would you please add some debug
> info to double confirm?
Hi Frider,
	Please ignore this comment, since there is -EPROBE_DEFER checking
, so you load sdma firmware by building sdma driver as module instead of
the above comment I mentioned? The warning log comes out during spi
transfer start and sdma firmware loading done, but if sdma driver building as
module could ensure firmware loading done in sdma_driver_probe_phase->
spi_imx_probe_phase, which means sdma firmware loading has been ready
before spi transfer start, hence no such warning message.

But I am not sure if all client drivers except spi are in good shape to support
' CONFIG_IMX_SDMA=m '. Besides, do you think 'dev_err_once ' instead of 'dev_err' is okay for you?