linux-kernel - [PATCH] mmc: atmel-mci: do not assume idle after atmci_request

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Message-Id: <20181019144024.31077-1-jonas@orbital-systems.com>
Date:   Fri, 19 Oct 2018 16:40:05 +0200
From:   Jonas Danielsson <jonas@...ital-systems.com>
To:     linux-kernel@...r.kernel.org
Cc:     Jonas Danielsson <jonas@...ital-systems.com>,
        Ludovic Desroches <ludovic.desroches@...rochip.com>,
        Ulf Hansson <ulf.hansson@...aro.org>, linux-mmc@...r.kernel.org
Subject: [PATCH] mmc: atmel-mci: do not assume idle after atmci_request_end

On our AT91SAM9260 board we use the same sdio bus for wifi and for the
sd card slot. This caused the atmel-mci to give the following splat on
the serial console:

  ------------[ cut here ]------------
  WARNING: CPU: 0 PID: 538 at drivers/mmc/host/atmel-mci.c:859 atmci_send_command+0x24/0x44
  Modules linked in:
  CPU: 0 PID: 538 Comm: mmcqd/0 Not tainted 4.14.76 #14
  Hardware name: Atmel AT91SAM9
  [<c000fccc>] (unwind_backtrace) from [<c000d3dc>] (show_stack+0x10/0x14)
  [<c000d3dc>] (show_stack) from [<c0017644>] (__warn+0xd8/0xf4)
  [<c0017644>] (__warn) from [<c0017704>] (warn_slowpath_null+0x1c/0x24)
  [<c0017704>] (warn_slowpath_null) from [<c033bb9c>] (atmci_send_command+0x24/0x44)
  [<c033bb9c>] (atmci_send_command) from [<c033e984>] (atmci_start_request+0x1f4/0x2dc)
  [<c033e984>] (atmci_start_request) from [<c033f3b4>] (atmci_request+0xf0/0x164)
  [<c033f3b4>] (atmci_request) from [<c0327108>] (mmc_start_request+0x280/0x2d0)
  [<c0327108>] (mmc_start_request) from [<c032800c>] (mmc_start_areq+0x230/0x330)
  [<c032800c>] (mmc_start_areq) from [<c03366f8>] (mmc_blk_issue_rw_rq+0xc4/0x310)
  [<c03366f8>] (mmc_blk_issue_rw_rq) from [<c03372c4>] (mmc_blk_issue_rq+0x118/0x5ac)
  [<c03372c4>] (mmc_blk_issue_rq) from [<c033781c>] (mmc_queue_thread+0xc4/0x118)
  [<c033781c>] (mmc_queue_thread) from [<c002daf8>] (kthread+0x100/0x118)
  [<c002daf8>] (kthread) from [<c000a580>] (ret_from_fork+0x14/0x34)
  ---[ end trace 594371ddfa284bd6 ]---

This is:
  WARN_ON(host->cmd);

This was fixed on our board by letting atmci_request_end determine what
state we are in. Instead of unconditionally setting it to STATE_IDLE on
STATE_END_REQUEST.

Signed-off-by: Jonas Danielsson <jonas@...ital-systems.com>
---
 drivers/mmc/host/atmel-mci.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/mmc/host/atmel-mci.c b/drivers/mmc/host/atmel-mci.c
index 0a0ebf3a0..c8a591d8a 100644
--- a/drivers/mmc/host/atmel-mci.c
+++ b/drivers/mmc/host/atmel-mci.c
@@ -1954,13 +1954,14 @@ static void atmci_tasklet_func(unsigned long priv)
 			}
 
 			atmci_request_end(host, host->mrq);
-			state = STATE_IDLE;
+			goto unlock; /* atmci_request_end() sets host->state */
 			break;
 		}
 	} while (state != prev_state);
 
 	host->state = state;
 
+unlock:
 	spin_unlock(&host->lock);
 }
 
-- 
2.17.2