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From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Joel Stanley <joel@jms.id.au>
Cc: linux-aspeed@lists.ozlabs.org, openbmc@lists.ozlabs.org,
	devicetree@vger.kernel.org, Andrew Jeffery <andrew@aj.id.au>,
	linux-kernel@vger.kernel.org,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>
Subject: [PATCH 04/14] fsi: master-gpio: Rename and adjust send delay
Date: Wed, 27 Jun 2018 09:25:55 +1000	[thread overview]
Message-ID: <20180626232605.13420-5-benh@kernel.crashing.org> (raw)
In-Reply-To: <20180626232605.13420-1-benh@kernel.crashing.org>

What the driver called "FSI_GPIO_PRIME_SLAVE_CLOCKS" is what
the FSI spec calls tSendDelay and should be 16 clocks by
default.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
---
 drivers/fsi/fsi-master-gpio.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/fsi/fsi-master-gpio.c b/drivers/fsi/fsi-master-gpio.c
index 1fd8b417939d..836587701ceb 100644
--- a/drivers/fsi/fsi-master-gpio.c
+++ b/drivers/fsi/fsi-master-gpio.c
@@ -18,6 +18,7 @@
 
 #define	FSI_GPIO_STD_DLY	1	/* Standard pin delay in nS */
 #define	FSI_ECHO_DELAY_CLOCKS	16	/* Number clocks for echo delay */
+#define	FSI_SEND_DELAY_CLOCKS	16	/* Number clocks for send delay */
 #define	FSI_PRE_BREAK_CLOCKS	50	/* Number clocks to prep for break */
 #define	FSI_BREAK_CLOCKS	256	/* Number of clocks to issue break */
 #define	FSI_POST_BREAK_CLOCKS	16000	/* Number clocks to set up cfam */
@@ -48,7 +49,6 @@
 #define	FSI_GPIO_CRC_SIZE	4
 #define	FSI_GPIO_MSG_ID_SIZE		2
 #define	FSI_GPIO_MSG_RESPID_SIZE	2
-#define	FSI_GPIO_PRIME_SLAVE_CLOCKS	20
 
 #define LAST_ADDR_INVALID		0x1
 
@@ -535,9 +535,12 @@ static int poll_for_response(struct fsi_master_gpio *master,
 	if (busy_count > 0)
 		trace_fsi_master_gpio_poll_response_busy(master, busy_count);
  fail:
-	/* Clock the slave enough to be ready for next operation */
+	/*
+	 * tSendDelay clocks, avoids signal reflections when switching
+	 * from receive of response back to send of data.
+	 */
 	local_irq_save(flags);
-	clock_zeros(master, FSI_GPIO_PRIME_SLAVE_CLOCKS);
+	clock_zeros(master, FSI_SEND_DELAY_CLOCKS);
 	local_irq_restore(flags);
 
 	return rc;
-- 
2.17.1

  parent reply	other threads:[~2018-06-26 23:54 UTC|newest]

Thread overview: 33+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-06-26 23:25 [PATCH 00/14] fsi: Fixes and Coldfire coprocessor offload Benjamin Herrenschmidt
2018-06-26 23:25 ` [PATCH 01/14] devres: Add devm_of_iomap() Benjamin Herrenschmidt
2018-06-26 23:25 ` [PATCH 02/14] fsi: Move code around to avoid forward declaration Benjamin Herrenschmidt
2018-06-26 23:25 ` [PATCH 03/14] fsi: Add mechanism to set the tSendDelay and tEchoDelay values Benjamin Herrenschmidt
2018-06-28  4:10   ` Joel Stanley
2018-06-26 23:25 ` Benjamin Herrenschmidt [this message]
2018-06-26 23:25 ` [PATCH 05/14] fsi: master-gpio: Add support for link_config Benjamin Herrenschmidt
2018-06-28  4:11   ` Joel Stanley
2018-06-26 23:25 ` [PATCH 06/14] fsi: master-gpio: Add more tracepoints Benjamin Herrenschmidt
2018-06-28  4:11   ` Joel Stanley
2018-07-12  2:01     ` Benjamin Herrenschmidt
2018-06-26 23:25 ` [PATCH 07/14] fsi: master-gpio: Remove unused definitions Benjamin Herrenschmidt
2018-06-28  4:11   ` Joel Stanley
2018-06-26 23:25 ` [PATCH 08/14] fsi: master-gpio: Remove "GPIO" prefix on some definitions Benjamin Herrenschmidt
2018-06-28  4:11   ` Joel Stanley
2018-06-26 23:26 ` [PATCH 09/14] fsi: master-gpio: Add missing release function Benjamin Herrenschmidt
2018-06-28  4:12   ` Joel Stanley
2018-06-26 23:26 ` [PATCH 10/14] fsi: Move various master definitions to a common header Benjamin Herrenschmidt
2018-06-28  4:12   ` Joel Stanley
2018-06-26 23:26 ` [PATCH 11/14] dt-bindings: fsi: Document binding for the fsi-master-ast-cf "device" Benjamin Herrenschmidt
2018-06-28  4:12   ` Joel Stanley
2018-07-03 22:30   ` Rob Herring
2018-07-04  1:16     ` Benjamin Herrenschmidt
2018-07-05 16:08       ` Rob Herring
2018-07-07  1:50         ` Benjamin Herrenschmidt
2018-06-26 23:26 ` [PATCH 12/14] fsi: master-ast-cf: Add new FSI master using Aspeed ColdFire Benjamin Herrenschmidt
2018-06-28  5:03   ` Joel Stanley
2018-06-26 23:26 ` [PATCH 13/14] arm: dts: OpenPower Romulus system can use coprocessor for FSI Benjamin Herrenschmidt
2018-06-28  4:12   ` Joel Stanley
2018-06-26 23:26 ` [PATCH 14/14] arm: dts: OpenPower Palmetto " Benjamin Herrenschmidt
2018-06-28  4:13   ` Joel Stanley
  -- strict thread matches above, loose matches on Subject: below --
2018-06-26 23:23 [PATCH 00/14] fsi: Fixes and Coldfire coprocessor offload Benjamin Herrenschmidt
2018-06-26 23:23 ` [PATCH 04/14] fsi: master-gpio: Rename and adjust send delay Benjamin Herrenschmidt
2018-06-28  4:10   ` Joel Stanley

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