linux-kernel - RE: [RESEND v6 06/13] spi: imx: fix ERR009165

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Date:   Tue, 10 Mar 2020 08:27:41 +0000
From:   Robin Gong <yibin.gong@....com>
To:     Sascha Hauer <s.hauer@...gutronix.de>
CC:     "vkoul@...nel.org" <vkoul@...nel.org>,
        "shawnguo@...nel.org" <shawnguo@...nel.org>,
        "u.kleine-koenig@...gutronix.de" <u.kleine-koenig@...gutronix.de>,
        "broonie@...nel.org" <broonie@...nel.org>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "festevam@...il.com" <festevam@...il.com>,
        "dan.j.williams@...el.com" <dan.j.williams@...el.com>,
        "mark.rutland@....com" <mark.rutland@....com>,
        "catalin.marinas@....com" <catalin.marinas@....com>,
        "will.deacon@....com" <will.deacon@....com>,
        "l.stach@...gutronix.de" <l.stach@...gutronix.de>,
        "martin.fuzzey@...wbird.group" <martin.fuzzey@...wbird.group>,
        "kernel@...gutronix.de" <kernel@...gutronix.de>,
        "linux-spi@...r.kernel.org" <linux-spi@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        dl-linux-imx <linux-imx@....com>,
        "dmaengine@...r.kernel.org" <dmaengine@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>
Subject: RE: [RESEND v6  06/13] spi: imx: fix ERR009165

On 2020/03/10 Sascha Hauer <s.hauer@...gutronix.de> wrote:
> On Tue, Mar 10, 2020 at 07:31:55PM +0800, Robin Gong wrote:
> > Change to XCH  mode even in dma mode, please refer to the below
> > errata:
> > https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.
> >
> nxp.com%2Fdocs%2Fen%2Ferrata%2FIMX6DQCE.pdf&amp;data=02%7C01%7C
> yibin.g
> >
> ong%40nxp.com%7Ccbabce268dfd4b0a0e2a08d7c4c62ff6%7C686ea1d3bc2b4c
> 6fa92
> >
> cd99c5c301635%7C0%7C1%7C637194227793913712&amp;sdata=Q5N49T4jgX
> TcdTzsB
> > 3D0saK2%2Fzj0R4gnJcGR%2Bd70Fm4%3D&amp;reserved=0
> >
> > Signed-off-by: Robin Gong <yibin.gong@....com>
> > Acked-by: Mark Brown <broonie@...nel.org>
> > ---
> >  drivers/spi/spi-imx.c | 17 ++++++++++-------
> >  1 file changed, 10 insertions(+), 7 deletions(-)
> >
> > diff --git a/drivers/spi/spi-imx.c b/drivers/spi/spi-imx.c index
> > f4f28a4..842a86e 100644
> > --- a/drivers/spi/spi-imx.c
> > +++ b/drivers/spi/spi-imx.c
> > @@ -585,8 +585,9 @@ static int mx51_ecspi_prepare_transfer(struct
> spi_imx_data *spi_imx,
> >  	ctrl |= mx51_ecspi_clkdiv(spi_imx, t->speed_hz, &clk);
> >  	spi_imx->spi_bus_clk = clk;
> >
> > +	/* ERR009165: work in XHC mode as PIO */
> >  	if (spi_imx->usedma)
> > -		ctrl |= MX51_ECSPI_CTRL_SMC;
> > +		ctrl &= ~MX51_ECSPI_CTRL_SMC;
> 
> 'ctrl' was read from the hardware. In the dma case it was set explicitly, but it
> was never cleared for a PIO transfer. This looked wrong before this patch. Now
> with this patch it looks even more wrong:
> We clear a bit that has never been set and we only do this for DMA, when for
> the PIO case it definitly must be cleared. Drop the if clause.
Good point, ACK.
> 
> >
> >  	writel(ctrl, spi_imx->base + MX51_ECSPI_CTRL);
> >
> > @@ -612,12 +613,14 @@ static int mx51_ecspi_prepare_transfer(struct
> > spi_imx_data *spi_imx,
> >
> >  static void mx51_setup_wml(struct spi_imx_data *spi_imx)  {
> > +	u32 tx_wml = 0;
> > +
> >  	/*
> >  	 * Configure the DMA register: setup the watermark
> >  	 * and enable DMA request.
> >  	 */
> >  	writel(MX51_ECSPI_DMA_RX_WML(spi_imx->wml - 1) |
> > -		MX51_ECSPI_DMA_TX_WML(spi_imx->wml) |
> > +		MX51_ECSPI_DMA_TX_WML(tx_wml) |
> 
> tx_wml is never assigned any other value than 0. Drop the variable.
That's prepared for 07/13 patch which may assign spi_imx->wml to tx_wml.
> 
> >  		MX51_ECSPI_DMA_RXT_WML(spi_imx->wml) |
> >  		MX51_ECSPI_DMA_TEDEN | MX51_ECSPI_DMA_RXDEN |
> >  		MX51_ECSPI_DMA_RXTDEN, spi_imx->base + MX51_ECSPI_DMA);
> @@ -1171,7
> > +1174,11 @@ static int spi_imx_dma_configure(struct spi_master *master)
> >  	tx.direction = DMA_MEM_TO_DEV;
> >  	tx.dst_addr = spi_imx->base_phys + MXC_CSPITXDATA;
> >  	tx.dst_addr_width = buswidth;
> > -	tx.dst_maxburst = spi_imx->wml;
> > +	/*
> > +	 * For ERR009165 with tx_wml = 0 could enlarge burst size to fifo size
> > +	 * to speed up fifo filling as possible.
> > +	 */
> > +	tx.dst_maxburst = spi_imx->devtype_data->fifo_size;
> >  	ret = dmaengine_slave_config(master->dma_tx, &tx);
> >  	if (ret) {
> >  		dev_err(spi_imx->dev, "TX dma configuration failed with %d\n",
> > ret); @@ -1265,10 +1272,6 @@ static int spi_imx_sdma_init(struct
> > device *dev, struct spi_imx_data *spi_imx,  {
> >  	int ret;
> >
> > -	/* use pio mode for i.mx6dl chip TKT238285 */
> > -	if (of_machine_is_compatible("fsl,imx6dl"))
> > -		return 0;
> 
> So with this patch it becomes possible to do DMA on i.MX6dl, but it is
> mentioned nowhere.
That's a common IP issue but caught on i.mx6dl at that time, so this time I didn't mention
i.mx6dl.
> 
> Sascha
> 
> --
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