linux-kernel - Re: [PATCH v5 05/11] spi: imx: Add support for loopback for ECSPI controllers

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Message-ID: <566600FF.1040905@gmail.com>
Date:	Mon, 7 Dec 2015 22:58:23 +0100
From:	Anton Bondarenko <anton.bondarenko.sama@...il.com>
To:	Sascha Hauer <s.hauer@...gutronix.de>
Cc:	broonie@...nel.org, b38343@...escale.com,
	linux-kernel@...r.kernel.org, linux-spi@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	vladimir_zapolskiy@...tor.com, jiada_wang@...tor.com
Subject: Re: [PATCH v5 05/11] spi: imx: Add support for loopback for ECSPI
 controllers



On 2015-12-07 10:27, Sascha Hauer wrote:
> On Sat, Dec 05, 2015 at 05:57:03PM +0100, Anton Bondarenko wrote:
>> Support for ECSPI loopback for IMX51, IMX53 and IMX6Q using TEST register.
>>
>> Signed-off-by: Mohsin Kazmi <mohsin_kazmi@...tor.com>
>> Signed-off-by: Anton Bondarenko <anton.bondarenko.sama@...il.com>
>> ---
>>   drivers/spi/spi-imx.c | 19 ++++++++++++++++---
>>   1 file changed, 16 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/spi/spi-imx.c b/drivers/spi/spi-imx.c
>> index 363276d..3525616 100644
>> --- a/drivers/spi/spi-imx.c
>> +++ b/drivers/spi/spi-imx.c
>> @@ -246,6 +246,9 @@ static bool spi_imx_can_dma(struct spi_master *master, struct spi_device *spi,
>>   #define MX51_ECSPI_STAT		0x18
>>   #define MX51_ECSPI_STAT_RR		(1 <<  3)
>>
>> +#define MX51_ECSPI_TEST			0x20
>> +#define MX51_ECSPI_LOOP			BIT(31)
>> +
>>   /* MX51 eCSPI */
>>   static unsigned int mx51_ecspi_clkdiv(unsigned int fin, unsigned int fspi,
>>   				      unsigned int *fres)
>> @@ -316,6 +319,7 @@ static int __maybe_unused mx51_ecspi_config(struct spi_imx_data *spi_imx,
>>   	u32 ctrl = MX51_ECSPI_CTRL_ENABLE, cfg = 0, dma = 0;
>>   	u32 tx_wml_cfg, rx_wml_cfg, rxt_wml_cfg;
>>   	u32 clk = config->speed_hz, delay;
>> +	u32 lpb = 0;
>>
>>   	/*
>>   	 * The hardware seems to have a race condition when changing modes. The
>> @@ -356,6 +360,12 @@ static int __maybe_unused mx51_ecspi_config(struct spi_imx_data *spi_imx,
>>   	writel(ctrl, spi_imx->base + MX51_ECSPI_CTRL);
>>   	writel(cfg, spi_imx->base + MX51_ECSPI_CONFIG);
>>
>> +	if (config->mode & SPI_LOOP)
>> +		lpb |= MX51_ECSPI_LOOP;
>> +
>> +	if ((readl(spi_imx->base + MX51_ECSPI_TEST) & MX51_ECSPI_LOOP) != lpb)
>> +		writel(lpb, spi_imx->base + MX51_ECSPI_TEST);
>> +
>>   	/*
>>   	 * Wait until the changes in the configuration register CONFIGREG
>>   	 * propagate into the hardware. It takes exactly one tick of the
>> @@ -1128,6 +1138,9 @@ static int spi_imx_probe(struct platform_device *pdev)
>>   	spi_imx = spi_master_get_devdata(master);
>>   	spi_imx->bitbang.master = master;
>>
>> +	spi_imx->devtype_data = of_id ? of_id->data :
>> +		(struct spi_imx_devtype_data *)pdev->id_entry->driver_data;
>> +
>>   	for (i = 0; i < master->num_chipselect; i++) {
>>   		int cs_gpio = of_get_named_gpio(np, "cs-gpios", i);
>>   		if (!gpio_is_valid(cs_gpio) && mxc_platform_info)
>> @@ -1154,10 +1167,10 @@ static int spi_imx_probe(struct platform_device *pdev)
>>   	spi_imx->bitbang.master->unprepare_message = spi_imx_unprepare_message;
>>   	spi_imx->bitbang.master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH;
>>
>> -	init_completion(&spi_imx->xfer_done);
>> +	if (is_imx51_ecspi(spi_imx))
>> +		spi_imx->bitbang.master->mode_bits |= SPI_LOOP;
>>
>> -	spi_imx->devtype_data = of_id ? of_id->data :
>> -		(struct spi_imx_devtype_data *) pdev->id_entry->driver_data;
>> +	init_completion(&spi_imx->xfer_done);
>
> Some unrelated lines are moved in these two hunks. Is this necessary or
> just some leftover from development?
>
> Sascha
>

Sascha,

This is necessary because is_imx51_ecspi function is base on content of 
spi_imx->devtype_data (see previous commit PATCH v5 04/11). I could try 
to move SPI_LOOP mode bit set to avoid change for completion initialization.

Regards, Anton
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