From ebc090e420d1fc3ed30fc9f0331ee95422c2bace Mon Sep 17 00:00:00 2001 From: Adrian Schmutzler Date: Thu, 27 Feb 2020 11:55:36 +0100 Subject: [PATCH] ath79: reduce spi-max-frequency to 50 MHz The introduction of ebf0d8dadeca ("ath79: add new ar934x spi driver") made the SPI memory unusable on devices with very high spi-max-frequency (104 MHz). Here's how the actual clock is calculated: (AHB_CLK/((CLOCK_DIVIDER+1)*2)) where AHB_CLK is a fixed clock (e.g. 200MHz on AR9331) and CLOCK_DIVIDER is the parameter we can set. Highest clock according to this formula is AHB_CLK/2 (100MHz, but that didn't work in device tests). The next possible value is AHB_CLK/4 (50MHz). Speeds between 50 MHz and 100 MHz will be rounded down, so using values higher than 50 MHz does not provide any benefit. Consequently, this patch reduces spi-max-frequency for all devices with values higher than 50 MHz to 50 MHz (effectively, this only affects devices with 104 MHz before this patch). Tested on GL.inet GL-AR150: Boot fails with 104 MHz but is successful with both 50 MHz and 80 MHz (fast-read), where the latter two yield identical read speeds. Fixes: ebf0d8dadeca ("ath79: add new ar934x spi driver") Signed-off-by: Adrian Schmutzler --- target/linux/ath79/dts/ar9330_glinet_gl-ar150.dts | 2 +- target/linux/ath79/dts/ar9330_pqi_air-pen.dts | 2 +- target/linux/ath79/dts/ar9331_8dev_carambola2.dts | 2 +- target/linux/ath79/dts/ar9331_embeddedwireless_dorin.dts | 2 +- target/linux/ath79/dts/ar9331_tplink_tl-mr3020-v1.dts | 2 +- target/linux/ath79/dts/ar9331_tplink_tl-mr3040-v2.dts | 2 +- 6 files changed, 6 insertions(+), 6 deletions(-) diff --git a/target/linux/ath79/dts/ar9330_glinet_gl-ar150.dts b/target/linux/ath79/dts/ar9330_glinet_gl-ar150.dts index 70754c905e..68e1995c76 100644 --- a/target/linux/ath79/dts/ar9330_glinet_gl-ar150.dts +++ b/target/linux/ath79/dts/ar9330_glinet_gl-ar150.dts @@ -86,7 +86,7 @@ flash@0 { compatible = "jedec,spi-nor"; - spi-max-frequency = <104000000>; + spi-max-frequency = <50000000>; reg = <0>; partitions { diff --git a/target/linux/ath79/dts/ar9330_pqi_air-pen.dts b/target/linux/ath79/dts/ar9330_pqi_air-pen.dts index 92484f9331..8537faa0f9 100644 --- a/target/linux/ath79/dts/ar9330_pqi_air-pen.dts +++ b/target/linux/ath79/dts/ar9330_pqi_air-pen.dts @@ -75,7 +75,7 @@ flash@0 { compatible = "jedec,spi-nor"; - spi-max-frequency = <104000000>; + spi-max-frequency = <50000000>; reg = <0>; partitions { diff --git a/target/linux/ath79/dts/ar9331_8dev_carambola2.dts b/target/linux/ath79/dts/ar9331_8dev_carambola2.dts index cc0320d652..ef244f0b55 100644 --- a/target/linux/ath79/dts/ar9331_8dev_carambola2.dts +++ b/target/linux/ath79/dts/ar9331_8dev_carambola2.dts @@ -73,7 +73,7 @@ flash@0 { compatible = "jedec,spi-nor"; - spi-max-frequency = <104000000>; + spi-max-frequency = <50000000>; reg = <0>; partitions { diff --git a/target/linux/ath79/dts/ar9331_embeddedwireless_dorin.dts b/target/linux/ath79/dts/ar9331_embeddedwireless_dorin.dts index 3489a972d4..4761b91093 100644 --- a/target/linux/ath79/dts/ar9331_embeddedwireless_dorin.dts +++ b/target/linux/ath79/dts/ar9331_embeddedwireless_dorin.dts @@ -68,7 +68,7 @@ flash@0 { compatible = "jedec,spi-nor"; - spi-max-frequency = <104000000>; + spi-max-frequency = <50000000>; reg = <0>; partitions { diff --git a/target/linux/ath79/dts/ar9331_tplink_tl-mr3020-v1.dts b/target/linux/ath79/dts/ar9331_tplink_tl-mr3020-v1.dts index 3cd5c130c8..97a058edf6 100644 --- a/target/linux/ath79/dts/ar9331_tplink_tl-mr3020-v1.dts +++ b/target/linux/ath79/dts/ar9331_tplink_tl-mr3020-v1.dts @@ -120,7 +120,7 @@ /* Spansion S25FL032PIF SPI flash */ flash@0 { compatible = "jedec,spi-nor"; - spi-max-frequency = <104000000>; + spi-max-frequency = <50000000>; reg = <0>; partitions { diff --git a/target/linux/ath79/dts/ar9331_tplink_tl-mr3040-v2.dts b/target/linux/ath79/dts/ar9331_tplink_tl-mr3040-v2.dts index e8a3dfbce7..5918e611dd 100644 --- a/target/linux/ath79/dts/ar9331_tplink_tl-mr3040-v2.dts +++ b/target/linux/ath79/dts/ar9331_tplink_tl-mr3040-v2.dts @@ -114,7 +114,7 @@ flash@0 { compatible = "jedec,spi-nor"; - spi-max-frequency = <104000000>; + spi-max-frequency = <50000000>; reg = <0>; partitions { -- 2.25.1