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From:   Shaokun Zhang <zhangshaokun@hisilicon.com>
To:     <linux-kernel@vger.kernel.org>
CC:     Nianyao Tang <tangnianyao@huawei.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Marc Zyngier <maz@kernel.org>,
        Shaokun Zhang <zhangshaokun@hisilicon.com>
Subject: [PATCH] irqchip/gic-v4: Fix non-stick page size error for setup GITS_BASER
Date:   Fri, 13 Mar 2020 16:46:35 +0800
Message-ID: <1584089195-63897-1-git-send-email-zhangshaokun@hisilicon.com>
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From: Nianyao Tang <tangnianyao@huawei.com>

There is an error when ITS is probed if hw GITS_BASER<2>
only supports psz=SZ_16K while GITS_BASER<1> only supports psz=SZ_4K.
In its_alloc_tables, it has updated GITS_BASER<1>.psz and uses
psz=SZ_4K for setup GITS_BASER<2>, and would fail in writing
GITS_BASER<2>.psz=SZ_4K. 4K PAGE is the smallest and shall stop retry
for other page sizes.

That latter GITS_BASER<n>.psz is larger than former, will lead
to similar error.

[    0.000000] ITS@0x0000000660000000: Virtual CPUs doesn't stick: ba1f0824404004ff ba1f0824404005ff
[    0.000000] ITS@0x0000000660000000: failed probing (-6)
[    0.000000] ITS: No ITS available, not enabling LPIs

From GIC SPEC document, it's allowed for this implematation, the latter
GITS_BASER<n>.psz is larger than the former. 
Let's fix this error with following patch.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Marc Zyngier <maz@kernel.org>
Signed-off-by: Nianyao Tang <tangnianyao@huawei.com>
Signed-off-by: Shaokun Zhang <zhangshaokun@hisilicon.com>
---
 drivers/irqchip/irq-gic-v3-its.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
index 83b1186..59bf8d6 100644
--- a/drivers/irqchip/irq-gic-v3-its.c
+++ b/drivers/irqchip/irq-gic-v3-its.c
@@ -2341,7 +2341,6 @@ static int its_alloc_tables(struct its_node *its)
 		}
 
 		/* Update settings which will be used for next BASERn */
-		psz = baser->psz;
 		cache = baser->val & GITS_BASER_CACHEABILITY_MASK;
 		shr = baser->val & GITS_BASER_SHAREABILITY_MASK;
 	}
-- 
1.9.1