[PATCH AUTOSEL 4.4 4/7] spi/zynqmp: remove entry that causes a cs glitch

[PATCH AUTOSEL 4.4 4/7] spi/zynqmp: remove entry that causes a cs glitch

[Sasha Levin]

From: Thommy Jakobsson <thommyj@gmail.com>

[ Upstream commit 5dd8304981ecffa77bb72b1c57c4be5dfe6cfae9 ]

In the public interface for chipselect, there is always an entry
commented as "Dummy generic FIFO entry" pushed down to the fifo right
after the activate/deactivate command. The dummy entry is 0x0,
irregardless if the intention was to activate or deactive the cs. This
causes the cs line to glitch rather than beeing activated in the case
when there was an activate command.

This has been observed on oscilloscope, and have caused problems for at
least one specific flash device type connected to the qspi port. After
the change the glitch is gone and cs goes active when intended.

The reason why this worked before (except for the glitch) was because
when sending the actual data, the CS bits are once again set. Since
most flashes uses mode 0, there is always a half clk period anyway for
cs to clk active setup time. If someone would rely on timing from a
chip_select call to a transfer_one, it would fail though.

It is unknown why the dummy entry was there in the first place, git log
seems to be of no help in this case. The reference manual gives no
indication of the necessity of this. In fact the lower 8 bits are a
setup (or hold in case of deactivate) time expressed in cycles. So this
should not be needed to fulfill any setup/hold timings.

Signed-off-by: Thommy Jakobsson <thommyj@gmail.com>
Reviewed-by: Naga Sureshkumar Relli <naga.sureshkumar.relli@xilinx.com>
Link: https://lore.kernel.org/r/20200224162643.29102-1-thommyj@gmail.com
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/spi/spi-zynqmp-gqspi.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/drivers/spi/spi-zynqmp-gqspi.c b/drivers/spi/spi-zynqmp-gqspi.c
index f23f36ebaf3dc..bd3945a5660a5 100644
--- a/drivers/spi/spi-zynqmp-gqspi.c
+++ b/drivers/spi/spi-zynqmp-gqspi.c
@@ -414,9 +414,6 @@ static void zynqmp_qspi_chipselect(struct spi_device *qspi, bool is_high)
 
 	zynqmp_gqspi_write(xqspi, GQSPI_GEN_FIFO_OFST, genfifoentry);
 
-	/* Dummy generic FIFO entry */
-	zynqmp_gqspi_write(xqspi, GQSPI_GEN_FIFO_OFST, 0x0);
-
 	/* Manually start the generic FIFO command */
 	zynqmp_gqspi_write(xqspi, GQSPI_CONFIG_OFST,
 			zynqmp_gqspi_read(xqspi, GQSPI_CONFIG_OFST) |
-- 
2.20.1


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[PATCH AUTOSEL 4.4 5/7] drm/exynos: dsi: propagate error value and silence meaningless warning

[Sasha Levin]

From: Marek Szyprowski <m.szyprowski@samsung.com>

[ Upstream commit 0a9d1e3f3f038785ebc72d53f1c409d07f6b4ff5 ]

Properly propagate error value from devm_regulator_bulk_get() and don't
confuse user with meaningless warning about failure in getting regulators
in case of deferred probe.

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Reviewed-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Inki Dae <inki.dae@samsung.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/gpu/drm/exynos/exynos_drm_dsi.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/exynos/exynos_drm_dsi.c b/drivers/gpu/drm/exynos/exynos_drm_dsi.c
index 12b03b3647034..1ee0b70472fd8 100644
--- a/drivers/gpu/drm/exynos/exynos_drm_dsi.c
+++ b/drivers/gpu/drm/exynos/exynos_drm_dsi.c
@@ -1899,8 +1899,9 @@ static int exynos_dsi_probe(struct platform_device *pdev)
 	ret = devm_regulator_bulk_get(dev, ARRAY_SIZE(dsi->supplies),
 				      dsi->supplies);
 	if (ret) {
-		dev_info(dev, "failed to get regulators: %d\n", ret);
-		return -EPROBE_DEFER;
+		if (ret != -EPROBE_DEFER)
+			dev_info(dev, "failed to get regulators: %d\n", ret);
+		return ret;
 	}
 
 	dsi->clks = devm_kzalloc(dev,
-- 
2.20.1


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[PATCH AUTOSEL 4.4 6/7] drm/exynos: dsi: fix workaround for the legacy clock name

[Sasha Levin]

From: Marek Szyprowski <m.szyprowski@samsung.com>

[ Upstream commit c0fd99d659ba5582e09625c7a985d63fc2ca74b5 ]

Writing to the built-in strings arrays doesn't work if driver is loaded
as kernel module. This is also considered as a bad pattern. Fix this by
adding a call to clk_get() with legacy clock name. This fixes following
kernel oops if driver is loaded as module:

Unable to handle kernel paging request at virtual address bf047978
 pgd = (ptrval)
 [bf047978] *pgd=59344811, *pte=5903c6df, *ppte=5903c65f
 Internal error: Oops: 80f [#1] SMP ARM
 Modules linked in: mc exynosdrm(+) analogix_dp rtc_s3c exynos_ppmu i2c_gpio
 CPU: 1 PID: 212 Comm: systemd-udevd Not tainted 5.6.0-rc2-next-20200219 #326
 videodev: Linux video capture interface: v2.00
 Hardware name: Samsung Exynos (Flattened Device Tree)
 PC is at exynos_dsi_probe+0x1f0/0x384 [exynosdrm]
 LR is at exynos_dsi_probe+0x1dc/0x384 [exynosdrm]
 ...
 Process systemd-udevd (pid: 212, stack limit = 0x(ptrval))
 ...
 [<bf03cf14>] (exynos_dsi_probe [exynosdrm]) from [<c09b1ca0>] (platform_drv_probe+0x6c/0xa4)
 [<c09b1ca0>] (platform_drv_probe) from [<c09afcb8>] (really_probe+0x210/0x350)
 [<c09afcb8>] (really_probe) from [<c09aff74>] (driver_probe_device+0x60/0x1a0)
 [<c09aff74>] (driver_probe_device) from [<c09b0254>] (device_driver_attach+0x58/0x60)
 [<c09b0254>] (device_driver_attach) from [<c09b02dc>] (__driver_attach+0x80/0xbc)
 [<c09b02dc>] (__driver_attach) from [<c09ade00>] (bus_for_each_dev+0x68/0xb4)
 [<c09ade00>] (bus_for_each_dev) from [<c09aefd8>] (bus_add_driver+0x130/0x1e8)
 [<c09aefd8>] (bus_add_driver) from [<c09b0d64>] (driver_register+0x78/0x110)
 [<c09b0d64>] (driver_register) from [<bf038558>] (exynos_drm_init+0xe8/0x11c [exynosdrm])
 [<bf038558>] (exynos_drm_init [exynosdrm]) from [<c0302fa8>] (do_one_initcall+0x50/0x220)
 [<c0302fa8>] (do_one_initcall) from [<c03dd02c>] (do_init_module+0x60/0x210)
 [<c03dd02c>] (do_init_module) from [<c03dbf44>] (load_module+0x1c0c/0x2310)
 [<c03dbf44>] (load_module) from [<c03dc85c>] (sys_finit_module+0xac/0xbc)
 [<c03dc85c>] (sys_finit_module) from [<c0301000>] (ret_fast_syscall+0x0/0x54)
 Exception stack(0xd979bfa8 to 0xd979bff0)
 ...
 ---[ end trace db16efe05faab470 ]---

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Reviewed-by: Andrzej Hajda <a.hajda@samsung.com>
Signed-off-by: Inki Dae <inki.dae@samsung.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/gpu/drm/exynos/exynos_drm_dsi.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/exynos/exynos_drm_dsi.c b/drivers/gpu/drm/exynos/exynos_drm_dsi.c
index 1ee0b70472fd8..77ff3eed65d62 100644
--- a/drivers/gpu/drm/exynos/exynos_drm_dsi.c
+++ b/drivers/gpu/drm/exynos/exynos_drm_dsi.c
@@ -1914,9 +1914,10 @@ static int exynos_dsi_probe(struct platform_device *pdev)
 		dsi->clks[i] = devm_clk_get(dev, clk_names[i]);
 		if (IS_ERR(dsi->clks[i])) {
 			if (strcmp(clk_names[i], "sclk_mipi") == 0) {
-				strcpy(clk_names[i], OLD_SCLK_MIPI_CLK_NAME);
-				i--;
-				continue;
+				dsi->clks[i] = devm_clk_get(dev,
+							OLD_SCLK_MIPI_CLK_NAME);
+				if (!IS_ERR(dsi->clks[i]))
+					continue;
 			}
 
 			dev_info(dev, "failed to get the clock: %s\n",
-- 
2.20.1


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