From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752069AbaBBR3o (ORCPT ); Sun, 2 Feb 2014 12:29:44 -0500 Received: from smtp1-g21.free.fr ([212.27.42.1]:59962 "EHLO smtp1-g21.free.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751862AbaBBR3n convert rfc822-to-8bit (ORCPT ); Sun, 2 Feb 2014 12:29:43 -0500 Date: Sun, 2 Feb 2014 18:30:00 +0100 From: Jean-Francois Moine To: Russell King - ARM Linux Cc: dri-devel@lists.freedesktop.org, Dave Airlie , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Rob Clark Subject: Re: [PATCH v5 02/23] drm/i2c: tda998x: check more I/O errors Message-ID: <20140202183000.1cf9ca9c@armhf> In-Reply-To: <20140202162057.GE26684@n2100.arm.linux.org.uk> References: <9ebf1fdd613b5747aefb3ee21c9c246d102f1a47.1390986082.git.moinejf@free.fr> <20140202162057.GE26684@n2100.arm.linux.org.uk> X-Mailer: Claws Mail 3.9.3 (GTK+ 2.24.22; arm-unknown-linux-gnueabihf) MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, 2 Feb 2014 16:20:58 +0000 Russell King - ARM Linux wrote: > On Sat, Jan 25, 2014 at 06:14:45PM +0100, Jean-Francois Moine wrote: > > This patch adds more error checking inn I2C I/O functions. > > In case of I/O error, this permits to avoid writing in bad controller > > pages, a bad chipset detection or looping when getting the EDID. > > I've just looked at this again, and spotted something: > > > -static uint8_t > > +static int > > reg_read(struct tda998x_priv *priv, uint16_t reg) > > { > > uint8_t val = 0; > > - reg_read_range(priv, reg, &val, sizeof(val)); > > + int ret; > > + > > + ret = reg_read_range(priv, reg, &val, sizeof(val)); > > + if (ret < 0) > > + return ret; > > So yes, this can return negative numbers. > > > @@ -1158,8 +1184,11 @@ tda998x_encoder_init(struct i2c_client *client, > > tda998x_reset(priv); > > > > /* read version: */ > > - priv->rev = reg_read(priv, REG_VERSION_LSB) | > > - reg_read(priv, REG_VERSION_MSB) << 8; > > + ret = reg_read(priv, REG_VERSION_LSB) | > > + (reg_read(priv, REG_VERSION_MSB) << 8); > > + if (ret < 0) > > + goto fail; > > + priv->rev = ret; > > Two issues here: > > 1. The additional parens are /really/ not required. > 2. What if reg_read(priv, REG_VERSION_MSB) returns a negative number? > > If we're going to the extent of attempting to make the read/write > functions return errors, we should at least handle errors generated > by them properly, otherwise it's pointless making them return errors. > > ret = reg_read(priv, REG_VERSION_LSB); > if (ret < 0) > goto fail; > > priv->rev = ret; > > ret = reg_read(priv, REG_VERSION_MSB); > if (ret < 0) > goto fail; > > priv->rev |= ret << 8; > > If you want it to look slightly nicer: > > int rev_lo, rev_hi; > > rev_lo = reg_read(priv, REG_VERSION_LSB); > rev_hi = reg_read(priv, REG_VERSION_MSB); > if (rev_lo < 0 || rev_hi < 0) { > ret = rev_lo < 0 ? rev_lo : rev_hi; > goto fail; > } > > priv->rev = rev_lo | rev_hi << 8; > > I'm happy to commit such a change after this patch to clean it up, or if > you want to regenerate your patch 2 and post /just/ that incorporating > this change. I think that my code works correctly: when there is an error, the result of reg_read() is minus the error code, and this error code is always lower than 8388607 (0x7fffff). Then, reg_read() << 8 will always be negative. Otherwise, I may redo a patch about the useless parenthesis. -- Ken ar c'hentañ | ** Breizh ha Linux atav! ** Jef | http://moinejf.free.fr/ From mboxrd@z Thu Jan 1 00:00:00 1970 From: moinejf@free.fr (Jean-Francois Moine) Date: Sun, 2 Feb 2014 18:30:00 +0100 Subject: [PATCH v5 02/23] drm/i2c: tda998x: check more I/O errors In-Reply-To: <20140202162057.GE26684@n2100.arm.linux.org.uk> References: <9ebf1fdd613b5747aefb3ee21c9c246d102f1a47.1390986082.git.moinejf@free.fr> <20140202162057.GE26684@n2100.arm.linux.org.uk> Message-ID: <20140202183000.1cf9ca9c@armhf> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Sun, 2 Feb 2014 16:20:58 +0000 Russell King - ARM Linux wrote: > On Sat, Jan 25, 2014 at 06:14:45PM +0100, Jean-Francois Moine wrote: > > This patch adds more error checking inn I2C I/O functions. > > In case of I/O error, this permits to avoid writing in bad controller > > pages, a bad chipset detection or looping when getting the EDID. > > I've just looked at this again, and spotted something: > > > -static uint8_t > > +static int > > reg_read(struct tda998x_priv *priv, uint16_t reg) > > { > > uint8_t val = 0; > > - reg_read_range(priv, reg, &val, sizeof(val)); > > + int ret; > > + > > + ret = reg_read_range(priv, reg, &val, sizeof(val)); > > + if (ret < 0) > > + return ret; > > So yes, this can return negative numbers. > > > @@ -1158,8 +1184,11 @@ tda998x_encoder_init(struct i2c_client *client, > > tda998x_reset(priv); > > > > /* read version: */ > > - priv->rev = reg_read(priv, REG_VERSION_LSB) | > > - reg_read(priv, REG_VERSION_MSB) << 8; > > + ret = reg_read(priv, REG_VERSION_LSB) | > > + (reg_read(priv, REG_VERSION_MSB) << 8); > > + if (ret < 0) > > + goto fail; > > + priv->rev = ret; > > Two issues here: > > 1. The additional parens are /really/ not required. > 2. What if reg_read(priv, REG_VERSION_MSB) returns a negative number? > > If we're going to the extent of attempting to make the read/write > functions return errors, we should at least handle errors generated > by them properly, otherwise it's pointless making them return errors. > > ret = reg_read(priv, REG_VERSION_LSB); > if (ret < 0) > goto fail; > > priv->rev = ret; > > ret = reg_read(priv, REG_VERSION_MSB); > if (ret < 0) > goto fail; > > priv->rev |= ret << 8; > > If you want it to look slightly nicer: > > int rev_lo, rev_hi; > > rev_lo = reg_read(priv, REG_VERSION_LSB); > rev_hi = reg_read(priv, REG_VERSION_MSB); > if (rev_lo < 0 || rev_hi < 0) { > ret = rev_lo < 0 ? rev_lo : rev_hi; > goto fail; > } > > priv->rev = rev_lo | rev_hi << 8; > > I'm happy to commit such a change after this patch to clean it up, or if > you want to regenerate your patch 2 and post /just/ that incorporating > this change. I think that my code works correctly: when there is an error, the result of reg_read() is minus the error code, and this error code is always lower than 8388607 (0x7fffff). Then, reg_read() << 8 will always be negative. Otherwise, I may redo a patch about the useless parenthesis. -- Ken ar c'henta? | ** Breizh ha Linux atav! ** Jef | http://moinejf.free.fr/ From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jean-Francois Moine Subject: Re: [PATCH v5 02/23] drm/i2c: tda998x: check more I/O errors Date: Sun, 2 Feb 2014 18:30:00 +0100 Message-ID: <20140202183000.1cf9ca9c@armhf> References: <9ebf1fdd613b5747aefb3ee21c9c246d102f1a47.1390986082.git.moinejf@free.fr> <20140202162057.GE26684@n2100.arm.linux.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Return-path: Received: from smtp1-g21.free.fr (smtp1-g21.free.fr [212.27.42.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 18C6010586C for ; Sun, 2 Feb 2014 09:29:41 -0800 (PST) In-Reply-To: <20140202162057.GE26684@n2100.arm.linux.org.uk> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dri-devel-bounces@lists.freedesktop.org Errors-To: dri-devel-bounces@lists.freedesktop.org To: Russell King - ARM Linux Cc: linux-arm-kernel@lists.infradead.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org List-Id: dri-devel@lists.freedesktop.org T24gU3VuLCAyIEZlYiAyMDE0IDE2OjIwOjU4ICswMDAwClJ1c3NlbGwgS2luZyAtIEFSTSBMaW51 eCA8bGludXhAYXJtLmxpbnV4Lm9yZy51az4gd3JvdGU6Cgo+IE9uIFNhdCwgSmFuIDI1LCAyMDE0 IGF0IDA2OjE0OjQ1UE0gKzAxMDAsIEplYW4tRnJhbmNvaXMgTW9pbmUgd3JvdGU6Cj4gPiBUaGlz IHBhdGNoIGFkZHMgbW9yZSBlcnJvciBjaGVja2luZyBpbm4gSTJDIEkvTyBmdW5jdGlvbnMuCj4g PiBJbiBjYXNlIG9mIEkvTyBlcnJvciwgdGhpcyBwZXJtaXRzIHRvIGF2b2lkIHdyaXRpbmcgaW4g YmFkIGNvbnRyb2xsZXIKPiA+IHBhZ2VzLCBhIGJhZCBjaGlwc2V0IGRldGVjdGlvbiBvciBsb29w aW5nIHdoZW4gZ2V0dGluZyB0aGUgRURJRC4KPiAKPiBJJ3ZlIGp1c3QgbG9va2VkIGF0IHRoaXMg YWdhaW4sIGFuZCBzcG90dGVkIHNvbWV0aGluZzoKPiAKPiA+IC1zdGF0aWMgdWludDhfdAo+ID4g K3N0YXRpYyBpbnQKPiA+ICByZWdfcmVhZChzdHJ1Y3QgdGRhOTk4eF9wcml2ICpwcml2LCB1aW50 MTZfdCByZWcpCj4gPiAgewo+ID4gIAl1aW50OF90IHZhbCA9IDA7Cj4gPiAtCXJlZ19yZWFkX3Jh bmdlKHByaXYsIHJlZywgJnZhbCwgc2l6ZW9mKHZhbCkpOwo+ID4gKwlpbnQgcmV0Owo+ID4gKwo+ ID4gKwlyZXQgPSByZWdfcmVhZF9yYW5nZShwcml2LCByZWcsICZ2YWwsIHNpemVvZih2YWwpKTsK PiA+ICsJaWYgKHJldCA8IDApCj4gPiArCQlyZXR1cm4gcmV0Owo+IAo+IFNvIHllcywgdGhpcyBj YW4gcmV0dXJuIG5lZ2F0aXZlIG51bWJlcnMuCj4gCj4gPiBAQCAtMTE1OCw4ICsxMTg0LDExIEBA IHRkYTk5OHhfZW5jb2Rlcl9pbml0KHN0cnVjdCBpMmNfY2xpZW50ICpjbGllbnQsCj4gPiAgCXRk YTk5OHhfcmVzZXQocHJpdik7Cj4gPiAgCj4gPiAgCS8qIHJlYWQgdmVyc2lvbjogKi8KPiA+IC0J cHJpdi0+cmV2ID0gcmVnX3JlYWQocHJpdiwgUkVHX1ZFUlNJT05fTFNCKSB8Cj4gPiAtCQkJcmVn X3JlYWQocHJpdiwgUkVHX1ZFUlNJT05fTVNCKSA8PCA4Owo+ID4gKwlyZXQgPSByZWdfcmVhZChw cml2LCBSRUdfVkVSU0lPTl9MU0IpIHwKPiA+ICsJCShyZWdfcmVhZChwcml2LCBSRUdfVkVSU0lP Tl9NU0IpIDw8IDgpOwo+ID4gKwlpZiAocmV0IDwgMCkKPiA+ICsJCWdvdG8gZmFpbDsKPiA+ICsJ cHJpdi0+cmV2ID0gcmV0Owo+IAo+IFR3byBpc3N1ZXMgaGVyZToKPiAKPiAxLiBUaGUgYWRkaXRp b25hbCBwYXJlbnMgYXJlIC9yZWFsbHkvIG5vdCByZXF1aXJlZC4KPiAyLiBXaGF0IGlmIHJlZ19y ZWFkKHByaXYsIFJFR19WRVJTSU9OX01TQikgcmV0dXJucyBhIG5lZ2F0aXZlIG51bWJlcj8KPiAK PiBJZiB3ZSdyZSBnb2luZyB0byB0aGUgZXh0ZW50IG9mIGF0dGVtcHRpbmcgdG8gbWFrZSB0aGUg cmVhZC93cml0ZQo+IGZ1bmN0aW9ucyByZXR1cm4gZXJyb3JzLCB3ZSBzaG91bGQgYXQgbGVhc3Qg aGFuZGxlIGVycm9ycyBnZW5lcmF0ZWQKPiBieSB0aGVtIHByb3Blcmx5LCBvdGhlcndpc2UgaXQn cyBwb2ludGxlc3MgbWFraW5nIHRoZW0gcmV0dXJuIGVycm9ycy4KPiAKPiAJcmV0ID0gcmVnX3Jl YWQocHJpdiwgUkVHX1ZFUlNJT05fTFNCKTsKPiAJaWYgKHJldCA8IDApCj4gCQlnb3RvIGZhaWw7 Cj4gCj4gCXByaXYtPnJldiA9IHJldDsKPiAKPiAJcmV0ID0gcmVnX3JlYWQocHJpdiwgUkVHX1ZF UlNJT05fTVNCKTsKPiAJaWYgKHJldCA8IDApCj4gCQlnb3RvIGZhaWw7Cj4gCj4gCXByaXYtPnJl diB8PSByZXQgPDwgODsKPiAKPiBJZiB5b3Ugd2FudCBpdCB0byBsb29rIHNsaWdodGx5IG5pY2Vy Ogo+IAo+IAlpbnQgcmV2X2xvLCByZXZfaGk7Cj4gCj4gCXJldl9sbyA9IHJlZ19yZWFkKHByaXYs IFJFR19WRVJTSU9OX0xTQik7Cj4gCXJldl9oaSA9IHJlZ19yZWFkKHByaXYsIFJFR19WRVJTSU9O X01TQik7Cj4gCWlmIChyZXZfbG8gPCAwIHx8IHJldl9oaSA8IDApIHsKPiAJCXJldCA9IHJldl9s byA8IDAgPyByZXZfbG8gOiByZXZfaGk7Cj4gCQlnb3RvIGZhaWw7Cj4gCX0KPiAKPiAJcHJpdi0+ cmV2ID0gcmV2X2xvIHwgcmV2X2hpIDw8IDg7Cj4gCj4gSSdtIGhhcHB5IHRvIGNvbW1pdCBzdWNo IGEgY2hhbmdlIGFmdGVyIHRoaXMgcGF0Y2ggdG8gY2xlYW4gaXQgdXAsIG9yIGlmCj4geW91IHdh bnQgdG8gcmVnZW5lcmF0ZSB5b3VyIHBhdGNoIDIgYW5kIHBvc3QgL2p1c3QvIHRoYXQgaW5jb3Jw b3JhdGluZwo+IHRoaXMgY2hhbmdlLgoKSSB0aGluayB0aGF0IG15IGNvZGUgd29ya3MgY29ycmVj dGx5OiB3aGVuIHRoZXJlIGlzIGFuIGVycm9yLCB0aGUKcmVzdWx0IG9mIHJlZ19yZWFkKCkgaXMg bWludXMgdGhlIGVycm9yIGNvZGUsIGFuZCB0aGlzIGVycm9yIGNvZGUgaXMKYWx3YXlzIGxvd2Vy IHRoYW4gODM4ODYwNyAoMHg3ZmZmZmYpLiBUaGVuLCByZWdfcmVhZCgpIDw8IDggd2lsbCBhbHdh eXMKYmUgbmVnYXRpdmUuCgpPdGhlcndpc2UsIEkgbWF5IHJlZG8gYSBwYXRjaCBhYm91dCB0aGUg dXNlbGVzcyBwYXJlbnRoZXNpcy4KCi0tIApLZW4gYXIgYydoZW50YcOxCXwJICAgICAgKiogQnJl aXpoIGhhIExpbnV4IGF0YXYhICoqCkplZgkJfAkJaHR0cDovL21vaW5lamYuZnJlZS5mci8KX19f X19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX18KZHJpLWRldmVsIG1h aWxpbmcgbGlzdApkcmktZGV2ZWxAbGlzdHMuZnJlZWRlc2t0b3Aub3JnCmh0dHA6Ly9saXN0cy5m cmVlZGVza3RvcC5vcmcvbWFpbG1hbi9saXN0aW5mby9kcmktZGV2ZWwK