From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pali =?utf-8?q?Roh=C3=A1r?= Subject: mmc does not work in qemu n900 Date: Mon, 26 Jan 2015 22:04:59 +0100 Message-ID: <201501262204.59305@pali> Mime-Version: 1.0 Content-Type: multipart/signed; boundary="nextPart2140942.rm5U7zV4qW"; protocol="application/pgp-signature"; micalg=pgp-sha1 Content-Transfer-Encoding: 7bit Return-path: Received: from mail-we0-f177.google.com ([74.125.82.177]:58237 "EHLO mail-we0-f177.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755573AbbAZVFC (ORCPT ); Mon, 26 Jan 2015 16:05:02 -0500 Sender: linux-mmc-owner@vger.kernel.org List-Id: linux-mmc@vger.kernel.org To: Chris Ball , Ulf Hansson Cc: linux-mmc@vger.kernel.org, linux-kernel@vger.kernel.org, Pavel Machek , Ivaylo Dimitrov , Sebastian Reichel , Aaro Koskinen --nextPart2140942.rm5U7zV4qW Content-Type: Text/Plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Hello, for unknown reason kernel in qemu n900 machine is not able to=20 detect internal eMMC memory. External SD card is detected without=20 problem. If I apply this one-line patch eMMC in qemu start working: diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c index 9584bff..0d4461c 100644 =2D-- a/drivers/mmc/core/core.c +++ b/drivers/mmc/core/core.c @@ -2337,6 +2337,9 @@ static int mmc_rescan_try_freq( return 0; if (!mmc_attach_sd(host)) return 0; + + mmc_go_idle(host); + if (!mmc_attach_mmc(host)) return 0; I played with mmc and qemu n900 a bit and also this simple patch=20 (without first) fix problem (that mmc is not detected by kernel): diff --git a/drivers/mmc/core/mmc_ops.c=20 b/drivers/mmc/core/mmc_ops.c index 3b044c5..0c93a2c 100644 =2D-- a/drivers/mmc/core/mmc_ops.c +++ b/drivers/mmc/core/mmc_ops.c @@ -157,6 +157,10 @@ int mmc_send_op_cond( =20 BUG_ON(!host); =20 + /* reset mmc before calling op_cond */ + memset(&cmd, 0, sizeof(struct mmc_command)); + mmc_wait_for_cmd(host, &cmd, MMC_CMD_RETRIES); + cmd.opcode =3D MMC_SEND_OP_COND; cmd.arg =3D mmc_host_is_spi(host) ? 0 : ocr; cmd.flags =3D MMC_RSP_SPI_R1 | MMC_RSP_R3 | MMC_CMD_BCR; =20 I have no idea where is problem. I also do not understand mmc=20 kernel code, but second patch I have on my HDD since 2.6.37. Can somebody with knowledge of mmc subsystem look at this=20 problem? Why any of these two patches fix problem when mmc is not=20 detected by kernel in qemu (machine n900)? Detection of mmc fails=20 because function mmc_send_op_cond() without one of above patches=20 fails. =2D-=20 Pali Roh=C3=A1r pali.rohar@gmail.com --nextPart2140942.rm5U7zV4qW Content-Type: application/pgp-signature; name=signature.asc Content-Description: This is a digitally signed message part. -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (GNU/Linux) iEYEABECAAYFAlTGq/sACgkQi/DJPQPkQ1LpbQCbB9rsxOTbfxx9Jw/lRHFG4fak bJ8An3uQy5wmH0DbPFFon01Y7LNIC/wZ =D3yF -----END PGP SIGNATURE----- --nextPart2140942.rm5U7zV4qW--