From: Marc Kleine-Budde <mkl@pengutronix.de>
To: netdev@vger.kernel.org
Cc: davem@davemloft.net, linux-can@vger.kernel.org,
kernel@pengutronix.de, Thomas Kopp <thomas.kopp@microchip.com>,
Marc Kleine-Budde <mkl@pengutronix.de>
Subject: [PATCH 02/13] can: mcp25xxfd: mcp25xxfd_probe(): add SPI clk limit related errata information
Date: Wed, 30 Sep 2020 22:18:05 +0200 [thread overview]
Message-ID: <20200930201816.1032054-3-mkl@pengutronix.de> (raw)
In-Reply-To: <20200930201816.1032054-1-mkl@pengutronix.de>
From: Thomas Kopp <thomas.kopp@microchip.com>
This patch adds a reference to the recent released MCP2517FD and MCP2518FD
errata sheets and paste the explanation.
The driver already implements the proposed fix.
Signed-off-by: Thomas Kopp <thomas.kopp@microchip.com>
Link: https://lore.kernel.org/r/20200925065606.358-1-thomas.kopp@microchip.com
[mkl: split into two patches, adjust subject and commit message]
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
---
.../net/can/spi/mcp25xxfd/mcp25xxfd-core.c | 19 ++++++++++++++-----
1 file changed, 14 insertions(+), 5 deletions(-)
diff --git a/drivers/net/can/spi/mcp25xxfd/mcp25xxfd-core.c b/drivers/net/can/spi/mcp25xxfd/mcp25xxfd-core.c
index 106dda8e5310..c094bb716256 100644
--- a/drivers/net/can/spi/mcp25xxfd/mcp25xxfd-core.c
+++ b/drivers/net/can/spi/mcp25xxfd/mcp25xxfd-core.c
@@ -2819,11 +2819,21 @@ static int mcp25xxfd_probe(struct spi_device *spi)
priv->devtype_data = *(struct mcp25xxfd_devtype_data *)
spi_get_device_id(spi)->driver_data;
- /* According to the datasheet the SPI clock must be less or
- * equal SYSCLOCK / 2.
+ /* Errata Reference:
+ * mcp2517fd: DS80000789B, mcp2518fd: DS80000792C 4.
+ *
+ * The SPI can write corrupted data to the RAM at fast SPI
+ * speeds:
+ *
+ * Simultaneous activity on the CAN bus while writing data to
+ * RAM via the SPI interface, with high SCK frequency, can
+ * lead to corrupted data being written to RAM.
+ *
+ * Fix/Work Around:
+ * Ensure that FSCK is less than or equal to 0.85 *
+ * (FSYSCLK/2).
*
- * It turns out, that the Controller is not stable at this
- * rate. Known good and bad combinations are:
+ * Known good and bad combinations are:
*
* MCP ext-clk SoC SPI SPI-clk max-clk parent-clk Status config
*
@@ -2836,7 +2846,6 @@ static int mcp25xxfd_probe(struct spi_device *spi)
* 2517 40 MHz atmel,sama5d27 atmel,at91rm9200-spi 16400000 Hz 82.00% 82000000 Hz good default
* 2518 40 MHz atmel,sama5d27 atmel,at91rm9200-spi 16400000 Hz 82.00% 82000000 Hz good default
*
- * Limit SPI clock to 85% of SYSCLOCK / 2 for now.
*/
priv->spi_max_speed_hz_orig = spi->max_speed_hz;
spi->max_speed_hz = min(spi->max_speed_hz, freq / 2 / 1000 * 850);
--
2.28.0
next prev parent reply other threads:[~2020-09-30 20:18 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-30 20:18 pull-request: can-next 2020-09-30 Marc Kleine-Budde
2020-09-30 20:18 ` [PATCH 01/13] can: mcp25xxfd: mcp25xxfd_handle_eccif(): add ECC related errata and update log messages Marc Kleine-Budde
2020-09-30 20:18 ` Marc Kleine-Budde [this message]
2020-09-30 20:18 ` [PATCH 03/13] can: mcp25xxfd: mcp25xxfd_ring_free(): fix memory leak during cleanup Marc Kleine-Budde
2020-09-30 20:18 ` [PATCH 04/13] can: mcp25xxfd: mcp25xxfd_irq(): add missing initialization of variable set_normal mode Marc Kleine-Budde
2020-09-30 20:18 ` [PATCH 05/13] dt-binding: can: mcp25xxfd: documentation fixes Marc Kleine-Budde
2020-09-30 20:18 ` [PATCH 06/13] dt-binding: can: mcp251xfd: narrow down wildcards in device tree bindings to "microchip,mcp251xfd" Marc Kleine-Budde
2020-09-30 20:18 ` [PATCH 07/13] can: mcp25xxfd: " Marc Kleine-Budde
2020-09-30 20:18 ` [PATCH 08/13] can: mcp251xfd: rename driver files and subdir to mcp251xfd Marc Kleine-Budde
2020-09-30 20:18 ` [PATCH 09/13] can: mcp251xfd: rename all user facing strings " Marc Kleine-Budde
2020-09-30 20:18 ` [PATCH 11/13] can: flexcan: initialize all flexcan memory for ECC function Marc Kleine-Budde
2020-09-30 20:18 ` [PATCH 12/13] can: flexcan: add flexcan driver for i.MX8MP Marc Kleine-Budde
2020-09-30 20:18 ` [PATCH 13/13] can: flexcan: disable runtime PM if register flexcandev failed Marc Kleine-Budde
2020-09-30 22:21 ` pull-request: can-next 2020-09-30 David Miller
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