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Message-ID: <5693C9A3.9040403@atmel.com>
Date: Mon, 11 Jan 2016 16:26:27 +0100
From: Nicolas Ferre <nicolas.ferre@...el.com>
To: Mans Rullgard <mans@...sr.com>, Mark Brown <broonie@...nel.org>,
<linux-spi@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
Cyrille Pitchen <cyrille.pitchen@...el.com>,
"Yang, Wenyou" <Wenyou.Yang@...el.com>
Subject: Re: [PATCH] spi: atmel: improve internal vs gpio chip-select choice
Le 08/01/2016 01:11, Mans Rullgard a écrit :
> The driver currently chooses between internal chip-select or gpio
> based on the existence of the cs-gpios DT property which fails on
> non-DT systems and also enforces the same choice for all devices.
Well, I fear that such a per-device choice may impact further the driver
than just moving a field from one structure to another... Moreover, I
have the feeling that it was not the objective of this patch.
> This patch makes the method per device instead of per controller
> and fixes the selection on non-DT systems. With these changes,
> the chip-select method for each device is chosen according to the
> following priority:
>
> 1. GPIO from device tree
> 2. GPIO from platform data
> 3. Internal chip-select
>
> Tested on AVR32 ATSTK1000.
This patch breaks the SAMA5D2 SPI support at least on most recent
linux-next (tested by Cyrille).
more remarks below...
> Signed-off-by: Mans Rullgard <mans@...sr.com>
> ---
> drivers/spi/spi-atmel.c | 44 ++++++++++++++++++++++----------------------
> 1 file changed, 22 insertions(+), 22 deletions(-)
>
> diff --git a/drivers/spi/spi-atmel.c b/drivers/spi/spi-atmel.c
> index aebad36391c9..8be07fb67d4d 100644
> --- a/drivers/spi/spi-atmel.c
> +++ b/drivers/spi/spi-atmel.c
> @@ -310,7 +310,6 @@ struct atmel_spi {
>
> bool use_dma;
> bool use_pdc;
> - bool use_cs_gpios;
> /* dmaengine data */
> struct atmel_spi_dma dma;
>
> @@ -324,6 +323,7 @@ struct atmel_spi {
> struct atmel_spi_device {
> unsigned int npcs_pin;
> u32 csr;
> + bool use_cs_gpio;
> };
>
> #define BUFFER_SIZE PAGE_SIZE
> @@ -388,7 +388,7 @@ static void cs_activate(struct atmel_spi *as, struct spi_device *spi)
> }
>
> mr = spi_readl(as, MR);
> - if (as->use_cs_gpios)
> + if (asd->use_cs_gpio)
> gpio_set_value(asd->npcs_pin, active);
> } else {
> u32 cpol = (spi->mode & SPI_CPOL) ? SPI_BIT(CPOL) : 0;
> @@ -405,7 +405,7 @@ static void cs_activate(struct atmel_spi *as, struct spi_device *spi)
>
> mr = spi_readl(as, MR);
> mr = SPI_BFINS(PCS, ~(1 << spi->chip_select), mr);
> - if (as->use_cs_gpios && spi->chip_select != 0)
> + if (asd->use_cs_gpio && spi->chip_select != 0)
> gpio_set_value(asd->npcs_pin, active);
> spi_writel(as, MR, mr);
> }
> @@ -434,7 +434,7 @@ static void cs_deactivate(struct atmel_spi *as, struct spi_device *spi)
> asd->npcs_pin, active ? " (low)" : "",
> mr);
>
> - if (!as->use_cs_gpios)
> + if (!asd->use_cs_gpio)
> spi_writel(as, CR, SPI_BIT(LASTXFER));
> else if (atmel_spi_is_v2(as) || spi->chip_select != 0)
> gpio_set_value(asd->npcs_pin, !active);
> @@ -1221,8 +1221,6 @@ static int atmel_spi_setup(struct spi_device *spi)
> csr |= SPI_BIT(CPOL);
> if (!(spi->mode & SPI_CPHA))
> csr |= SPI_BIT(NCPHA);
> - if (!as->use_cs_gpios)
> - csr |= SPI_BIT(CSAAT);
>
> /* DLYBS is mostly irrelevant since we manage chipselect using GPIOs.
> *
> @@ -1233,21 +1231,28 @@ static int atmel_spi_setup(struct spi_device *spi)
> csr |= SPI_BF(DLYBS, 0);
> csr |= SPI_BF(DLYBCT, 0);
>
> - /* chipselect must have been muxed as GPIO (e.g. in board setup) */
> - npcs_pin = (unsigned long)spi->controller_data;
> -
> - if (!as->use_cs_gpios)
> - npcs_pin = spi->chip_select;
> - else if (gpio_is_valid(spi->cs_gpio))
> - npcs_pin = spi->cs_gpio;
> -
> asd = spi->controller_state;
> if (!asd) {
> asd = kzalloc(sizeof(struct atmel_spi_device), GFP_KERNEL);
> if (!asd)
> return -ENOMEM;
>
> - if (as->use_cs_gpios) {
> + npcs_pin = (unsigned long)spi->controller_data;
> +
> + if (gpio_is_valid(spi->cs_gpio)) {
The bug may come from here as the logic is somehow inverted and a "0" is
a valid gpio according to this gpio_is_valid() function. So we may take
this conditional branch instead of the third one in the sama5d2 case.
> + /* GPIO from DT */
> + npcs_pin = spi->cs_gpio;
> + asd->use_cs_gpio = true;
> + } else if (npcs_pin && gpio_is_valid(npcs_pin)) {
> + /* GPIO from platform data */
> + asd->use_cs_gpio = true;
> + } else {
> + /* internal chip-select */
> + npcs_pin = spi->chip_select;
> + asd->use_cs_gpio = false;
> + }
> +
> + if (asd->use_cs_gpio) {
> ret = gpio_request(npcs_pin, dev_name(&spi->dev));
> if (ret) {
> kfree(asd);
> @@ -1262,6 +1267,8 @@ static int atmel_spi_setup(struct spi_device *spi)
> spi->controller_state = asd;
> }
>
> + if (!asd->use_cs_gpio)
> + csr |= SPI_BIT(CSAAT);
> asd->csr = csr;
>
> dev_dbg(&spi->dev,
> @@ -1569,13 +1576,6 @@ static int atmel_spi_probe(struct platform_device *pdev)
>
> atmel_get_caps(as);
>
> - as->use_cs_gpios = true;
> - if (atmel_spi_is_v2(as) &&
I don't see this atmel_spi_is_v2() test in the resulting code anymore:
did you make sure that the v1 of the peripheral is protected?
> - !of_get_property(pdev->dev.of_node, "cs-gpios", NULL)) {
> - as->use_cs_gpios = false;
> - master->num_chipselect = 4;
This line is pretty important: you mustn't remove it blindly!
> - }
> -
> as->use_dma = false;
> as->use_pdc = false;
> if (as->caps.has_dma_support) {
>
So, sorry but it's a NACK for me.
Bye,
--
Nicolas Ferre
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